Appeal from the Circuit Court of Stephenson County. Nos. 96-CF-437, 96-CF-446 Honorable Charles R. Hartman, Judge, Presiding.
 The opinion of the court was delivered by: Justice Grometer
 Following the denial of his motions to suppress evidence, defendant, Barry W. Miller, pleaded guilty in the circuit court of Stephenson County to one count of possession with intent to deliver 900 grams or more of a substance containing cocaine (720 ILCS 570/401(a)(2)(D) (West 1996)) (case No. 96--CF--437) and one count of possession with intent to deliver more than 500 grams of a substance containing cannabis (720 ILCS 550/5(e) (West 1996)) (case No. 96--CF--446). The trial court sentenced defendant to concurrent sentences of 25 years' imprisonment on the former conviction and seven years' imprisonment on the latter conviction. Subsequently, defendant filed a pro se petition for relief pursuant to the Post-Conviction Hearing Act (the Act) (725 ILCS 5/122--1 et seq. (West 1998)), alleging various violations of his constitutional rights. Defendant's petition was later amended by appointed counsel. After an evidentiary hearing, the trial court modified defendant's sentence but otherwise denied defendant's petition.
 On appeal, defendant reasserts a claim that he raised in his petition for post-conviction relief. Namely, defendant argues that trial counsel was ineffective at the hearing on the motion to suppress evidence relating to his conviction in case No. 96--CF--437, because trial counsel failed to introduce evidence that the cocaine seized was discovered in a duffel bag that was zipped closed. According to defendant, had trial counsel presented this evidence, the result of the suppression hearing would have been different and he would not have pleaded guilty. We agree with defendant. Accordingly, we reverse the decision of the trial court denying defendant's petition for post-conviction relief, vacate defendant's guilty plea in case No. 96--CF--437, and remand the cause for further proceedings.
 The facts underlying this appeal reveal that in separate indictments filed on December 19, 1996, defendant was charged with unlawful possession with intent to deliver more than 900 grams of a substance containing cocaine (720 ILCS 570/401(a)(2)(D) (West 1996)) and unlawful possession with intent to deliver 500 grams or more of a substance containing cannabis (720 ILCS 550/5(e) (West 1996)). On June 20, 1997, defendant filed separate motions to suppress evidence relating to both charges. Relevant here, the motion relating to the former charge alleged that on December 14, 1996, law enforcement officials illegally seized cocaine from a locked storage cabinet located at 1225 W. Harrison Street, Freeport, Illinois. A hearing on defendant's motion was held on July 7, 1997.
 The only witness at the suppression hearing was Michael DeMong. DeMong testified that he had rented the single-family home located at 1225 W. Harrison Street for seven years. In late 1995, DeMong permitted defendant to use the house. Although DeMong gave defendant a key to the premises, he also retained a key for himself. In August 1996, DeMong moved to his girlfriend's house. However, DeMong continued to rent the home on Harrison Street and receive mail there. In addition, DeMong's cat resided at the house, and DeMong left some of his clothing and furniture there. According to DeMong, he visited the house every other day to feed and check on his cat. DeMong stated that defendant would also feed the cat and that defendant kept a sofa at the home. Defendant did not contribute to the rent, however, and DeMong was unsure if defendant stayed overnight.
 The Harrison Street residence had two built-in storage cabinets, one of which was locked with a padlock belonging to DeMong. DeMong allowed defendant to use the locked cabinet free of charge, and he gave defendant the only two padlock keys that he possessed. DeMong stored a currency collection and some baseball cards in the locked cabinet. However, because he did not have a key to the padlock, DeMong stated that he would have had to pry open the cabinet or ask defendant to open it if he wanted to retrieve his property.
 On December 14, 1996, DeMong voluntarily went to the Freeport police department for an interview. DeMong told police that he saw contraband inside the storage cabinet a couple of months prior to December 14. The police escorted DeMong to 1225 W. Harrison Street and conducted a warrantless search of the premises, with DeMong's consent. DeMong informed the police that defendant had the only keys to the padlock on the storage cabinet. With DeMong's consent, the police forcibly removed the padlock from the storage cabinet and recovered a large quantity of a substance later identified as cocaine. DeMong was not charged with any drug-related offenses.
 In the argument that followed, defendant's attorney asserted that although defendant did not have exclusive possession of the Harrison Street residence, he did have exclusive possession of the locked storage cabinet. Thus, counsel argued, the police acted without effective third-party consent when they opened the storage cabinet without defendant's permission. The trial court disagreed and denied defendant's motion to suppress. According to the court, defendant had no expectation of privacy in the locked cabinet because DeMong and defendant shared the cabinet. The court also opined that DeMong and defendant were engaged in a "joint venture." The court therefore reasoned that DeMong had authority to consent to a search of the locked cabinet.
 On July 22, 1997, following a conference held pursuant to Supreme Court Rule 402 (177 Ill. 2d R. 402), the parties reached a plea agreement. Under the terms of the plea, defendant agreed to plead guilty in case No. 96--CF--437 in exchange for a sentence of 25 years' imprisonment and a street value fine of $100,000. In case No. 96--CF--446, defendant agreed to a plea of guilty in exchange for a sentence of seven years' imprisonment and a street value fine of $1,500. The sentences were to run concurrently. In addition, with respect to case No. 96--CF--437, the trial court admonished defendant that he was subject to a two-year term of mandatory supervised release in addition to any prison sentence. Following additional admonishments, the trial court determined that defendant's plea was voluntary.
 The prosecutor then presented the factual basis for the plea. The prosecutor stated that in the early morning hours of December 14, 1996, the police executed a search warrant for a residence located at 727 American Street, Freeport, Illinois. Defendant was sleeping at the location, and the police found 738.1 grams of cannabis and 15.8 grams of a substance containing cocaine. Defendant later admitted that the substances were his. The prosecutor further stated that later on December 14, 1996, police searched a locked storage cabinet at 1225 W. Harrison Street, Freeport, Illinois, with the consent of DeMong, the lessee of the premises. Inside the cabinet, the police found a duffel bag. DeMong told the police that the duffel bag belonged to defendant. The duffel bag was opened. Stored inside a plastic bag within the duffel bag was 1,097.3 grams of a substance containing cocaine. The plastic bag bore defendant's fingerprints. After the defense stipulated to the factual basis, the court concluded that there was a sufficient basis upon which to enter a finding of guilty on both charges. The court then admonished defendant regarding his postplea and appellate options. Defendant did not file any postplea motions, and he did not seek appellate review.
 On February 4, 1999, defendant filed, inter alia, a pro se petition for relief under the Act and a motion for the appointment of counsel. On September 1, 1999, the trial court appointed the public defender's office to represent defendant on his petition. After a number of changes in counsel, public defender Robert Miller (Miller) was appointed to represent defendant. On August 28, 2001, Miller filed a second supplemental post-conviction petition. In his petition, defendant alleged that (1) trial counsel was ineffective at the hearing on the motion to suppress evidence relating to his conviction for possession with intent to deliver cocaine because (a) trial counsel failed to elicit evidence that the cocaine was found in a sealed duffel bag, (b) trial counsel incorrectly cautioned defendant not to testify at the suppression hearing because his testimony could be used against him in the State's case in chief, (c) trial counsel failed to elicit necessary and relevant testimony about the third-party consent to and the scope of the search, and (d) trial counsel failed to competently and properly elicit testimony regarding the circumstances of the evidentiary seizure and to properly argue the law to the facts; (2) defendant was incorrectly admonished at the time of sentencing that he would be required to serve two years of mandatory supervised release when the applicable term was actually three years; (3) trial counsel was ineffective for failing to follow through on defendant's request that counsel file a motion to withdraw defendant's guilty plea; (4) trial counsel was ineffective for failing to pursue a fitness evaluation for defendant, knowing that defendant had not been taking prescribed psychotropic medication; (5) the trial court improperly induced him to plead guilty by suggesting at the Rule 402 (177 Ill. 2d R. 402) conference that defendant was "looking at a potential upper half of the statutory max sentence of 60 years"; and (6) trial counsel was ineffective for improperly inducing defendant to plead guilty by making factual misrepresentations to defendant. According to defendant, these errors rendered his guilty plea involuntary.
 The cause proceeded to an evidentiary hearing, which commenced on September 12, 2001. At the evidentiary hearing, defendant's trial counsel testified that he began practicing law in 1977 as an assistant State's Attorney in Cook County. His tenure in the State's Attorney's office included 13 months in the felony trial division. In October 1980, counsel entered private practice, concentrating in criminal felony defense. Trial counsel estimated that 60% to 70% of his cases involve drug charges, and he stated that he files motions to suppress in appropriate cases.
 With respect to defendant's suppression hearing, counsel stated that he was unable to recall much about defendant's case. Nevertheless, he opined that he put forth his best efforts in arguing the motion to suppress. Counsel believed that the closed duffel bag found inside the locked storage cabinet was not material because the police had already received permission to open the storage cabinet. According to counsel, DeMong's consent to open the locked storage cabinet extended to opening anything inside the ...