The opinion of the court was delivered by: Justice Freeman
 Docket No. 95311-Agenda 15-September 2003.
 Following a bench trial, the circuit court of Cook County convicted defendant, Elizabeth Ehlert, of the first degree murder of her newborn child (Ill. Rev. Stat. 1989, ch. 38, par. 9-1(a)), and sentenced her to 30 years in prison. The appellate court reversed, finding the evidence insufficient to prove the child was born alive. 335 Ill. App. 3d 467. We granted the State's petition for leave to appeal. 177 Ill. 2d R. 315(a). For the reasons that follow, we affirm the judgment of the appellate court.
 On August 21, 1990, defendant gave birth in her bedroom, in the home she shared with her two sons, her father, and her fiancé, Steven King. Two days later employees of the Salt Creek Park District discovered the baby's corpse in a nearby lake. A creek that ran behind defendant's house fed into the lake. Defendant's conviction for murder was reversed on appeal because the prosecution presented irrelevant and highly prejudicial evidence at defendant's jury trial. People v. Ehlert, 274 Ill. App. 3d 1026 (1995).
 On retrial, the prosecution presented several witnesses who testified that between April and mid-August 1990, defendant repeatedly told them she was not pregnant. She told the witnesses that she had a cancerous tumor and she had seen several doctors about it.
 King, who first met defendant in January 1990, testified that he moved in with her shortly thereafter. In April 1990, King noticed that defendant was gaining weight. Defendant told King that she had a growth or a cyst for which she had seen a doctor. In May 1990, defendant told King that she was bleeding and had received treatment from a doctor. They also discussed the need for a dilation and curettage. Defendant twice scheduled the procedure but was not able to have the surgery done. On July 18, defendant told King that she had ovarian cancer. Later in July, defendant told King that she had seen another doctor, and, in that doctor's opinion, the tumors she had were not cancerous. Appointments to remove the tumors were cancelled because defendant told King she was bleeding. Subsequently, on August 17, defendant called King at work. She was hysterical. When King came home, defendant told King that tests at the doctor's office showed she was actually six to eight weeks pregnant but the fetus was dead. She also told King that the doctor gave her a shot to induce an abortion within 48 hours.
 Around 3 a.m. on August 21, 1990, defendant woke King up and told him she was in labor. King got out of bed. A few minutes later, defendant began screaming in pain. Rather than remain at her side and provide assistance, King left the bedroom because he did not want to see the miscarriage or the fetus. He did not turn the light on in the bedroom or the hallway. He did not press the panic alarm buttons on the security system in the hallway, which could have brought assistance from the police or paramedics. King further testified that he was hysterical, crying, frightened. He began pacing the hallway, living room and kitchen, and ventured into the basement. Twenty to thirty minutes elapsed. King then told defendant he was calling the paramedics. Defendant told King that her labor was almost over and asked him to get a plastic bag. He got a brown and green plastic bag from the cabinet under the kitchen sink. When he was 15 to 20 steps from the bedroom, he heard a single cry, lasting about two seconds. He took a few more steps down the hallway and asked defendant about the noise. Defendant replied he must have heard the family dog, which was in the bedroom. King did not question defendant further. Instead, without entering the bedroom, King reached in with the bag and, from the bed, defendant reached out and took the bag.
 King testified that he next went to the living room area because he was not doing well emotionally. He did not hear any cries, sounds of choking or gasping for breath. He observed defendant, in her bathrobe, exit the bedroom and enter the bathroom. Defendant was not carrying the bag. She stayed in the bathroom for five minutes. During that time King did not hear any cries from the bedroom. Defendant returned to the bedroom. Again, without entering the bedroom, King repeatedly asked defendant if she was alright. Defendant told him to calm down. He heard some rustling as she picked up the bag but did not hear any crying or gasps for breath. He went back to the living room and from there observed defendant leave the bedroom with the plastic bag, which looked half full. He did not ask her what she planned to do with the bag but inquired again if she was alright. Defendant went to the kitchen area and King heard the back door slam. He went into the kitchen. Defendant was not there. He did not look to see where defendant went. Defendant returned two minutes later. When he asked her what she had done with the bag, she responded that she had thrown it into the creek. Defendant returned to the bedroom, and King could hear that she was in pain, screaming. He did not call the paramedics or press the alarm panic buttons. Defendant asked him to come into the bedroom and he entered the room for the first time. Defendant, in bed, was in the process of delivering or had just delivered the afterbirth. King cleaned up by pulling the towels and sheets from under her, placing them in another plastic bag and taking the bag to the kitchen for later disposal.
 In the morning, King was upset and crying. Defendant contacted King's mother, Mary Coward, who came over to the house. Coward asked King why he was upset. He related the whole episode to her and told her that he heard a baby cry. Later that day, King asked defendant about the cry he heard. She indicated that he had either heard the dog or imagined that he heard a cry.
 On September 6, 1990, King was questioned at the police station. In a written statement, he told police that he was in the hallway with hands folded clenched, during the course of defendant's labor. Defendant asked him to get a bag from the kitchen. As he returned with the bag, he thought he heard a baby cry. King then told the police that he would like to see an attorney and was informed that would not be necessary. At that point, King did not feel like a suspect. Later that same day, King received a telephone call from Commander McGregor, who told him that he did not think it was necessary for King to spend a lot of money on a lawyer. On cross-examination, King admitted that prior to the police interview, he was convinced he had either imagined the cry or heard the family dog. Also, at defendant's first trial, King testified that at the conclusion of the police interview he believed he was a suspect in the case and hired an attorney.
 Mary Coward testified that at approximately 9 a.m. on August 21, 1990, King called to say that defendant had the miscarriage and that he would call her later. That afternoon, defendant called to say that King was very upset and defendant asked Coward to come over. Once at the house, Coward sat next to King on the bed and comforted him. Coward nowhere testified that King told her he heard a baby cry.
 Police officers who spoke with defendant on September 6, 1990, testified that she told them she had miscarried a fetus 15 weeks old and flushed it down her toilet. Police told her they had talked to King. Defendant first said she threw the miscarriage in the garbage, then she said King threw it in the garbage. When officers said King told them a different story, defendant said she did not remember what happened, but King's account was probably true because "he doesn't lie." Police testified defendant admitted that she lied to King, and she had not seen any doctors throughout her pregnancy.
 Further testimony showed that defendant told police her water broke two days before the birth, when she fell while trying to retrieve her son's toy from a tree in her yard. She placed the fetus in a garbage bag and left the bag by a tree near the bank of the creek out back. When police asked if she threw the bag into the creek, she said, "No, unless you want me to say I did it, then I did it." She then asked to have the baby buried next to defendant's mother. In another interview, defendant told police that her ex-husband, not King, was the father of the baby. Defendant admitted that she had sexual relations with her ex-husband frequently in November 1989.
 A few days later defendant called the police to say that she could not live with herself and wanted to tell them the truth. She asked police to assure her that King would take care of her children if she went to jail. Later she told police that when she went to the bathroom after delivering the dead fetus, King went to the bedroom, picked up the bloody towels and the baby and threw them out.
 Dr. Mitra Kalelkar, assistant chief medical examiner for Cook County, testified at trial that when she completed the autopsy she could not determine to a reasonable degree of medical certainty that the baby had been born alive. She admitted that she found no unusual cause of death, so her "suspicion was that the baby drowned." On direct examination, the prosecutor asked Dr. Kalelkar whether, at the completion of the autopsy, she "form[ed] an opinion within a reasonable degree of medical certainty as to whether or not the baby was born alive." Dr. Kalelkar answered:
"At that time I had a suspicion that this baby was born alive and
that the cause of death would be drowning; and pursuant to that
suspicion, which I related to the police officers, I instructed
them to investigate further."
 Dr. Kalelkar later reiterated that after the autopsy she told police she "could not tell for sure whether it had been born alive."
 After police advised Dr. Kalelkar of their investigation, she concluded in December 1990 that the baby had been born alive and it had drowned. Dr. Kalelkar relied on evidence that defendant had lied to several persons about her pregnancy and her visits with doctors, and, most particularly, she relied on King's statement to police that he thought he heard a baby cry.
 Dr. Kalelkar further testified she saw no evidence in the decomposing corpse of any natural disease process. She found air in the lungs, hemorrhage on the skull due to natural causes, and some blood on the umbilical cord. Dr. Kalelkar admitted that the air she found in the lungs could have resulted from decomposition rather than breathing. She also stated that "there is no specific way of telling whether that rip [of the umbilical cord] was ante mortem or post-mortem." Blood may remain in the umbilical cord after the baby dies. Lastly, while the hemorrhaging suggested that the baby was alive when the head went through the vaginal canal, it did not show that the baby survived the birthing process.
 On cross-examination, Dr. Kalelkar admitted that a baby could die due to partial placental abruption. Furthermore, a baby could go into shock if it lost 60 milliliters of blood in the birthing process.
 Two pathologists testified on defendant's behalf. Both pathologists agreed with Dr. Kalelkar that the autopsy findings could not support a finding to a reasonable degree of medical certainty that the baby was born alive. Dr. John Pless stated that the hemorrhage on the skull could occur even if the fetus had already died. Dr. Pless noted that if placental abruption killed the fetus shortly before delivery, one would expect findings like those present here. He further stated that a fall from a tree could cause the placenta to detach from the uterine wall and result in fetal death. The force of the fall need not be great if the trauma occurred at a place that maximized impact on the placenta. Dr. Pless testified that the baby could also have died from blood loss in the birthing process or obstruction of the airway. Water and bacteria probably would have eliminated any mucus plugs that might have caused asphyxiation.
 Dr. Pless also agreed with Dr. Kalelkar that no marks on the body showed disease or physical injury. He noted that decomposition probably would have eliminated any evidence the baby died from infection. He also agreed with other doctors that a newborn faces a greater risk of death from asphyxiation or blood loss in an unattended home birth than in a hospital delivery.
 Dr. Robert Kirschner found there was sufficient evidence to conclude that the baby was alive when labor began. However, he found the evidence insufficient to show that the baby survived labor. Dr. Kirschner testified that even if the baby was alive at birth, it may have died from failure to clear its airways, blood loss or infection. He noted that, if a child had marked respiratory distress at the time of birth, it might give a feeble cry, then die. He agreed with the prosecutor that a cry would show live birth.
 At the conclusion of the trial, the court expressly found credible King's testimony that he heard a baby cry. The court recognized that King might have adequate motive to lie and to tell the police that he heard a baby cry. However, had King wanted to minimize his involvement it would have been better for him to deny that the baby was born alive. The court found King's testimony, together with the medical testimony, sufficient to show that the baby was born alive. The court concluded that defendant was guilty of murder.
 As noted by the appellate court, the circuit court did not comment on the medical testimony that the baby may have died after a live birth from various non-criminal causes. Also, the circuit court did not make any findings as to the cause of the baby's death or the criminal acts defendant committed resulting in the baby's death. The court sentenced defendant to 30 years in prison.
 On appeal, defendant argued that the evidence was insufficient to show that the baby was born alive. Further, defendant maintained that, if the baby was born alive, the evidence was insufficient to show that defendant performed any act after birth to cause the death of the baby or that defendant had the mental state required in a prosecution for murder. The appellate court agreed that the evidence was insufficient to prove live birth and reversed defendant's conviction. 335 Ill. App. 3d at 474. Because of its resolution of the issue of live birth, the court did not address the additional arguments for reversal.
 We granted the State's petition for leave to appeal.
 In this court, defendant contends the evidence was insufficient to prove her guilty beyond a reasonable doubt. Defendant reprises her arguments that the State failed to show that the baby was born alive and, if the baby was born alive, that defendant committed a criminal act resulting in the death and defendant had the requisite mental state for murder.
 A criminal conviction will not be set aside on appeal unless the evidence is so improbable or unsatisfactory that there remains a reasonable doubt of the defendant's guilt. People v. Tenney, 205 Ill. 2d 411, 427 (2002). The question on review is whether, after viewing the evidence in the light most favorable to the prosecution, any rational fact finder could have found defendant guilty beyond a reasonable doubt. People v. Brown, 185 Ill. 2d 229, 247 (1998); People v. Eyler, 133 Ill. 2d 173, 191 (1989). This standard of review applies in all criminal cases whether the evidence is direct or circumstantial. Tenney, 205 Ill. 2d at 427; People v. Gilliam, 172 Ill. 2d 484, 515 (1996).
 As noted above, the circuit court convicted defendant of the murder of her newborn. Proof of an offense requires proof of two concepts: first, that a crime occurred, or the corpus delicti, and second, that it was committed by the person charged. People v. Cloutier, 156 Ill. 2d 483, 503 (1993). In a prosecution for murder, the corpus delicti consists of the fact of death and the fact that death was produced by a criminal agency. People v. Garrett, 62 Ill. 2d 151, 172 (1975). In addition, where the State alleges that the defendant has killed her newborn, the State must prove that the infant was born alive. People v. Greer, 79 Ill. 2d 103, 110 (1980); People v. Ryan, 9 Ill. 2d 467, 471 (1956). It is axiomatic that a defendant cannot be convicted of the murder of a person who has already died. W. LaFave, Substantive Criminal Law §14.1, at 419 (2d ed. 2003).
 The appellate court believed that the State failed to prove defendant's baby was born alive. In particular, the appellate court found insufficient the State's evidence that the baby showed signs of independent life once expelled from defendant's womb. The appellate court noted agreement between the prosecution's medical expert and defense experts that the physical findings alone did not prove live birth to a reasonable degree of medical certainty. 335 Ill. App. 3d at 471. The appellate court further noted that in reaching her conclusion that the baby was born alive, Dr. Kalelkar relied on King's statement to police that he thought he heard a cry. 335 Ill. App. 3d at 471. And, although Dr. Kalelkar recited evidence that defendant did not want the child and lied to neighbors about the pregnancy, she did not explain why an unwanted child would have a better chance of surviving the birth process or how that evidence in any way showed live birth. 335 Ill. App. 3d at 471. Lastly, the appellate court considered, and found wanting as proof of live birth, King's testimony that he heard a baby cry. 335 Ill. App. 3d at 471. The court found it significant that King did not see the baby when he heard the cry. 335 Ill. App. 3d at 471. The baby could have cried during the birthing process, and King could not testify otherwise. 335 Ill. App. 3d at 471.
 Because the appellate court found insufficient the State's evidence that the baby was born alive, the court did not consider defendant's alternate arguments that the evidence was insufficient to prove either criminal agency or the requisite mental state for murder. 335 Ill. App. 3d at 468.
 In this court, the State argues the appellate court failed to apply the proper standard of review, that is, the appellate court failed to consider the facts in the light most favorable to the State, because the appellate court did not accept the fact that the baby cried. We disagree with the State's reading of the appellate court opinion. We believe the appellate court applied the appropriate standard of review.
 The State also urges that we discard the common law requirement that a baby must be totally expelled from the mother's womb and establish independent life before it is considered alive. The State asserts that the common law requirement, necessary because of the lack of medical knowledge and high infant mortality rates prevalent in the 18th century, is now antiquated. According to the State, medical advances have eliminated the need for a presumption of death during childbirth. The State asks us to adopt the view of the court in People v. Chavez, 77 Cal. App. 2d 621, 176 P.2d 92 (1947), that a viable fetus "in the process of being born" is a human being within the meaning of the homicide statutes.
 In Greer this court held that to be born alive a fetus must be totally expelled from the mother and show a clear sign of independent vitality. 79 Ill. 2d at 103. In urging that we adopt the reasoning of Chavez, the State is thus asking that we reconsider our ruling in Greer. In keeping with the doctrine of stare decisis, prior decisions should not be overruled absent good cause or compelling reasons. People v. Robinson, 187 Ill. 2d 461, 463-64 (1999); Moehle v. Chrysler Motors Corp., 93 Ill. 2d 299, 304 (1982). Further, we note that the State has raised arguments in this case that were considered by the court in Greer. We need not opine on the merits of the State's arguments, however, because we note an alternate basis for reversal of defendant's conviction. Defendant argues, and we agree, that even assuming the baby was born alive, the evidence was insufficient to show that death resulted from defendant's criminal agency.
 The State's theory of the case was that defendant, having hidden her pregnancy, gave birth to a live baby, placed the baby into a plastic bag, and either threw the bag into the creek or placed the bag next to the creek where an animal presumably dragged it into the creek. To prove this theory, the State presented evidence from King, defendant's paramour. King's testimony was that, when he was 15 to 20 steps from the bedroom, he heard a single cry, lasting about two seconds. King proceeded down the hallway to the bedroom. Without entering the bedroom, King reached in with the bag and, from the bed, defendant reached out and took the bag. King testified further that, after he handed the plastic bag to defendant, he did not hear any cries, sounds of choking or gasping for breath. Defendant left the baby unattended in the bedroom for five minutes. During that time, King did not hear any cries from the bedroom. King saw no signs of motion in the bag when defendant took the bag from the house.
 The State also relied on the testimony of the medical examiner, Dr. Kalelkar. At the time of the autopsy, Dr. Kalelkar found no unusual cause of death. No marks on the baby revealed foul play. Dr. Kalelkar testified on direct examination that, after performing an autopsy, she surmised that the baby drowned. Dr. Kalelkar distinguished between cause of death and manner of death: "The manner basically is the circumstances surrounding death" and could be natural, homicide, suicide, accident, or undetermined. After Dr. Kalelkar performed the autopsy, she suspected that the baby was born alive because the body had hemorrhaging on the head, aerated lungs, antemortem bleeding around the umbilical cord, and no natural diseases. Dr. Kalelkar then stated both that she did and that she did not determine the cause of death at the time of the autopsy to a reasonable degree of medical certainty. On direct examination, Dr. Kalelkar initially asserted, "At the time when I did the autopsy, *** I did not form an opinion. I verbalized to the police officers what my suspicions were or what I thought had happened to this child, and I instructed them to go and get or to investigate the matter further." When asked by the prosecutor when she formed her opinion regarding the cause of death, Dr. Kalelkar responded, "As to the cause of death was [sic] pretty obvious at the time that I did the autopsy because of the fact that the baby was recovered from water." The prosecutor clarified that he was addressing the cause of death, not the manner of death. Dr. Kalelkar then stated:
"In my opinion, and I so verbalized it to the police officers who
were present at the time of the autopsy, that based on the fact
that this body was recovered from water and based on the fact
there was no evidence of any other cause of death, injuries or
natural disease processes, the cause of death would be drowning."
 Thus, Dr. Kalelkar apparently determined the cause of death at the time of the autopsy, but did not determine the manner of death until she consulted with the police. Still, on the death certificate, she handwrote "pending police investigation" in the space for cause of death and left blank the space for manner of death.
 After Dr. Kalelkar advised the police of her suspicions, the police later advised her of the results from their investigation, which confirmed her suspicions, including her initial impression that the infant was born alive. In fact, Dr. Kalelkar observed that a "very significant" part of the police report was the fact that King "heard a sound which was akin to a baby crying." Dr. Kalelkar continued: "[H]earing the baby cry is an indication that a baby is born alive, and my physical findings showed that there was air in the lungs. Now granted that air in the lungs could have come from decomposition changes, but given this fact as well as the physical findings and all the other facts surrounding this case, everything tied together." Dr. Kalelkar listed the manner of death "based on all the circumstances" as homicide.
 On cross-examination, however, Dr. Kalelkar's account of her opinions changed. She testified that at the time of the autopsy, she could establish neither a cause nor a manner of death:
"Q. And at the end of the time that you completed that autopsy
you told those police officers that you could not determine for