from the Circuit Court of Kane County. No. 08-CF-1707
Honorable Timothy Q. Sheldon and M. Karen Simpson, Judges,
JUSTICE BURKE delivered the judgment of the court, with
opinion. Justice Birkett concurred in the judgment and
opinion. Justice Hutchinson specially concurred, with
1 In July 1990, Guadalupe Montano, the wife of defendant,
Aurelio Montano, went missing, and her body was never found.
The State's theory was that defendant, motivated by
jealousy, strangled Guadalupe with a rope, wrapped her in a
rug, buried her at a horse farm with the help of his brother,
told other family members about the killing, and moved the
body before the police could find it. In 2014, a jury found
defendant guilty of first-degree murder, and the trial court
imposed a sentence of natural life imprisonment.
2 On appeal, defendant argues that he is entitled to a new
trial because the court erred in admitting evidence that, 17
years after Guadalupe's disappearance, three detector
dogs alerted to the scent of human remains on the rug, which
was found buried in an outdoor area of the horse farm.
Defendant argues that the evidence did not meet the standard
of reliability set forth in Frye v. United States,
293 F. 1013 (D.C. Cir. 1923), and that the error was
compounded by the State's closing argument.
3 Defendant contends that the human-remains-detector-dog
evidence is analogous to bloodhound trailing evidence that
has been deemed inadmissible to show any factual proposition
in a criminal case. See People v. Cruz, 162 Ill.2d
314, 369-73 (1994). The State responds that the evidence is
more like the narcotics-detector-dog evidence deemed
admissible in People v. Moore, 294 Ill.App.3d 410
(1998), where the dog alerted to the defendant's car even
though no drugs were subsequently found in it. This case
presents the thorny issue of whether a trial court should
follow what is arguably Cruz's bright-line
prohibition against odor-detector-dog evidence or reexamine
the reliability of the underlying science as contemplated by
subsequent supreme court decisions. Here, the trial court
reexamined the underlying science, concluded that the State
presented an adequate foundation for the admission of the
evidence, and found the evidence reliable. We need not decide
whether the trial court erred in admitting the
human-remains-detector-dog evidence, because the overwhelming
evidence of defendant's guilt rendered any potential
error harmless beyond a reasonable doubt.
4 I. BACKGROUND
5 A. Frye Hearing
6 The State filed a pretrial motion in limine
seeking to introduce expert testimony regarding
human-remains-detector-dog "alerts" used during
searches. The State proposed testimony that, in this case,
three dogs gave positive alerts on the rug and the area where
it was found.
7 Dr. Susan Marie Stejskal testified that she had a Ph.D. in
toxicology with a minor in pathology. Dr. Stejskal's
credentials also included an undergraduate degree in animal
science and a veterinary technology program certificate of
completion. Dr. Stejskal testified that she was experienced
in the field of veterinary medicine, both as a licensed
veterinary technician and with a substantial history of
working with tracking dogs. Dr. Stejskal acknowledged on
cross-examination that, although she had participated in 80
to 100 trained canine searches for human remains, she
actually discovered human remains 7 or 8 times. She explained
that the infrequency was the result of her services being
requested to rule out areas of interest, such as in cold
8 The trial court found Dr. Stejskal to be an expert on the
subjects of the anatomy and physiology of canine olfaction
systems, forensic taphonomy (the study of postmortem changes
and decomposition of humans), and the training and deployment
of human-remains-detector dogs.
9 Dr. Stejskal testified that a human-remains-detector dog
serves as a tool to locate missing persons through the
science of canine olfaction and forensic taphonomy. Dr.
Stejskal described the olfactory system as the nostrils and
turbinates, or coiled pathways in bone through which air
passes when inhaled.
10 Inside the pathways of the turbinates, the air is filtered
by ciliated epithelial cells, humidified, and warmed before
it travels to the lungs. The odor that a human or dog detects
consists of volatile organic compounds in water vapor
suspended in the air. The turbinates contain olfactory
sensory cells with chemoreceptors that detect these compounds
and send messages through nerves to the olfactory bulb, which
processes scent. The chemoreceptors are like taste buds in
that distinct chemicals activate different cells to spark an
electrical current to the brain.
11 The olfactory systems of dogs and humans work in similar
ways, but dogs' sense of smell is far superior. First,
dogs and humans have differently designed nostrils. When a
human inhales and exhales, he or she will often breathe the
same air and recirculate it. In contrast, a dog's
nostrils shunt air to the side every time when exhaled, so
different air is inhaled with each breath.
12 Second, humans have 5 million olfactory sensory cells
while Dachshunds have 125 million, German Shepherds have 225
million, and bloodhounds have 300 million. Also, a German
Shepherd inhales about five times as much air as a human,
because the dog's turbinates are much more extensively
coiled. The extensive coiling provides about 20 times more
surface area of olfactory sensory cells.
13 Third, the canine olfactory bulb, which processes the
electrical signals sent by the chemoreceptors, is about 40
times larger than a human's. Using photography as an
analogy, Dr. Stejskal likened human smell to an "old
fuzzy Polaroid" and canine smell to a high definition
photograph, with extraordinary detail. Dr. Stejskal explained
that a human perceives the world primarily through his or her
eyes, but a dog perceives the world through its nose.
14 Dogs can be trained to locate human remains because their
physiology gives them the unique ability to distinguish
particular scents. When a detector dog encounters something
it has been trained to detect, the dog will "become
very, very interested in that odor" and exhibit a change
in behavior in that they breathe by sniffing. When a dog
switches from normal breathing to sniffing, more of the odor
is sent through the turbinates. Each time they take a breath,
dogs experience a scent as if they are encountering it for
the first time. They do not experience "olfactory
fatigue, " unlike humans who become desensitized to a
scent after continuous exposure.
15 Dr. Stejskal gave, without objection, a Power Point
presentation to describe forensic taphonomy, or the
scientific processes of human decomposition and the
postmortem changes that occur in different environments. The
four main stages of decomposition are the dying of cells,
early decomposition, putrefaction, and decay or
16 After a person dies, cells begin to die from elevated
acidity levels. The cells that die first have the highest
energy demand and blood supply, like in the heart and lungs.
17 In early decomposition, the body goes through (1) algor
mortis, or a decrease in body temperature; (2) livor mortis,
or the gravitational pooling of blood; and (3) rigor mortis,
or stiffening due to the contraction of muscle fibers. The
duration of each mortis depends on environmental conditions.
18 Putrefaction is "the stage of decomposition which we
associate with bloating and gas and smells" caused by
microbes and bacteria that reproduce as they break down cells
into carbohydrates, fats, and proteins. The body becomes very
fragile, and "skin slippage" occurs, in which skin
can pull away from the body and become attached to an object,
such as a tarp, that might have covered it. The cells begin
to separate from one another, internal organs break down, and
liquefaction occurs, where parts of the body turn to liquid
and spread to the environment. The body goes from bloated to
flattened. The carbohydrates, fats, and proteins are broken
down further into simpler building blocks. The final stage is
decay, or postputrefaction, where the rest of the tissues
break down. Eventually, skeletal remains are all that is left
19 Many different chemicals are produced during the different
stages of human decomposition occurring in different
conditions, and dogs can be trained to identify the odors.
For example, bloating causes methane and hydrogen sulfide
gases. Also, when a body is in an environment with low oxygen
levels and high water levels, certain bacteria can produce
adipocere, or "grave wax." Adipocere emits a strong
pungent odor. If tissues are in an area without the additive
effect of soil microbes, the chemical composition will be
slightly different. Dr. Stejskal testified that the Oak Ridge
National Laboratory at the University of Tennessee, Florida
International University, and the Federal Bureau of
Investigation (FBI) have researched the different chemicals
and the odors they produce.
20 Dr. Stejskal also testified to the training of dogs to
detect human remains. Dr. Stejskal had been involved in such
training for 10 years, but she was not involved in the
training of the dogs used in this case. According to Dr.
Stejskal, training a detector dog consists of repeatedly
exposing the dog to the source of a particular odor and then
rewarding the dog each time it demonstrates interest in that
odor. The dog is then trained to perform an "alert"
that connects the discovery of the odor to a behavior that is
rewarded. Specifically, human-remains-detector dogs are
trained by exposing them to the scent of human remains in
different stages of decomposition and in different
environments, creating a "library" of recognizable
scents. Environmental conditions affect the chemicals and
odors that are produced. The dogs also are exposed to
nonhuman remains to differentiate the chemical profiles of
21 Dr. Stejskal testified that many different organizations
use human-remains-detector dogs, sometimes referred to as
Scientific Working Group Dogs (SWGDOGs). The FBI uses them as
"victim recovery dogs, " and the U.S. military uses
"human remains recovery dogs" to find mass graves
and missing service members. The Netherlands and the United
Kingdom also have used dogs in their searches for human
remains. The Federal Emergency Management Agency (FEMA) has
mostly used rescue dogs, but has also used
human-remains-detector dogs, such as after the September 11,
2001, terror attacks in New York City and Washington, D.C.,
and after Hurricane Katrina in New Orleans. Now FEMA
certifies human-remains-detector dogs throughout the country.
22 Dr. Stejskal testified that dogs can be trained to detect
many types of substances, including human remains,
explosives, and narcotics, although actual human remains are
not used in the training. For example, the Department of
Homeland Security uses dogs to detect agricultural products,
such as meats, vegetables, and plants. Also, the Department
of Customs and Border Patrol uses dogs trained to detect
narcotics and explosives.
23 On very limited cross-examination, the defense questioned
Dr. Stejskal about the chemical and nonchemical differences
between the remains of humans and animals.
24 Dr. Stejskal opined that the field of training and
deploying human-remains-detector dogs is widely accepted in
the scientific community. She did not testify about whether a
dog could alert on a location 17 years after it was alleged
to have had contact with human remains.
25 Under Frye, the trial court deemed admissible the
evidence of the three canine alerts on the rug and the area
where it was found. The court found that the
human-remains-detector-dog evidence constituted science that
was not novel and was generally accepted within the
26 B. Trial
27 1. July 1990
28 The trial commenced on October 28, 2013. Maribel Montano,
the daughter of defendant and Guadalupe, testified that her
mother disappeared in July 1990. At the time, Maribel was 10
years old and lived with her parents in Aurora. Maribel
testified that her parents argued "very often" and
that defendant often started the arguments, accusing
Guadalupe of wearing clothes that were too revealing and
riding to work with a male coworker. Maribel had a closer
relationship with defendant than with Guadalupe, who worked a
lot and was "more distant."
29 Maribel described the last time she saw her mother. One
early afternoon in July 1990, defendant and Maribel prepared
to drive to the Aurora home of her aunt, Maria Montalvo, and
her husband. Maribel told Guadalupe goodbye and remembered
seeing her light a cigarette. Defendant dropped off Maribel
at the Montalvo home and returned the next day, driving
Guadalupe's gray Firebird, which defendant did not
usually drive. When Maribel entered the car, defendant said
that Guadalupe had left with another man.
30 Upon returning home, Maribel noticed a mess in her
mother's room. The bed had not been made, and clothes and
Guadalupe's open purse were on the floor. Maribel did not
look inside the purse, but she noticed that Guadalupe's
wallet was open with a driver's license and social
security card inside. Maribel also saw Guadalupe's
jewelry on the vanity, including rings that she never took
31 Maribel described an area rug in the living room of her
home. The rug was woven with a design consisting of squares
on the border and palm trees. At some point after the
disappearance, Maribel noticed that the rug was missing, and
she did not see it again until 2008 when a detective showed
it to her. The State presented a rug as an exhibit, and
Maribel identified it as the rug from her living room, though
she could not recall whether it was in the house on the day
that Guadalupe disappeared. Maribel moved out 9 or 10 months
after Guadalupe disappeared, and the rug was not in the home
at that time.
32 Narcisa Montano, defendant's older sister, testified
to a visit from defendant in July 1990. At the time, Narcisa
had a good relationship with Guadalupe but defendant had not
visited her or her children for six years. One day, defendant
came to her house. Defendant seemed "nervous and
strange, as if he were drunk or something." Defendant
told Narcisa to go to his house with him. Narcisa agreed
because she saw that defendant had a gun in his waistband or
pocket. Defendant displayed the gun, and Narcisa felt
threatened. As defendant drove, he told Narcisa that "he
had sent [Guadalupe] to another world" and that "he
had already sent the snake to another world, to hell."
Narcisa asked why, and defendant responded that he "sent
her to hell" for cheating on him.
33 When Narcisa and defendant arrived at defendant's
house, he said that she needed to go with him to the horse
farm on Hobson Road, where their brother, Juan Montano, and
his son, Roberto Montano, lived and worked. If she did not
go, defendant threatened, she would "be in the ground
just like [Guadalupe]."
34 Narcisa walked into the house and saw Guadalupe's body
sitting against the wall at the entry to the bathroom.
Guadalupe, who was wearing a nightgown and socks, "was
there sitting down, leaning against the wall, and she had a
piece of rope on her neck." Defendant told Narcisa that
he had strangled Guadalupe.
35 Soon thereafter, Narcisa's children arrived at the
house but stayed outside, and defendant directed Narcisa to
tell them to leave. The children left and defendant
"grabbed the body and he put it in a little rug."
Narcisa was too scared at the time to remember any details
about the rug, other than that it had a design.
36 Narcisa acknowledged that her testimony before the grand
jury was dissimilar in certain respects. She previously
testified that, when she went to defendant's home and saw
Guadalupe's body, it was already rolled up in a rug.
Because she was nervous, she did not mention during her grand
jury testimony that she saw Guadalupe's entire body.
Narcisa now testified that her trial testimony was the truth
and that she saw defendant place Guadalupe's body in the
37 Narcisa testified that, after defendant rolled
Guadalupe's body into the rug, he put the body into the
rear of his truck. Defendant and Narcisa rode to the horse
farm, looking for Juan. Roberto's wife, Maria Summaria,
answered the door and said that Juan was at work. Narcisa
went inside with Maria, and defendant left. Later that night,
defendant returned and told Narcisa that they could leave.
Defendant told her not to tell anyone what she had seen or
"he would send me and my children to hell." Narcisa
identified two exhibits: one was the rug that defendant used
to transport Guadalupe's body, and the other was a rope
that looked like the one on Guadalupe. The rug was the same
one identified by Maribel.
38 On cross-examination, Narcisa acknowledged that she did
not contact the police after seeing Guadalupe's body,
even when she learned of their investigation. Narcisa was
scared of defendant's threats. Narcisa told the police
her story only after they said that other family members had
confessed their involvement in Guadalupe's disappearance.
39 On November 14, 2007, Narcisa told Detective Guillermo
Trujillo that she had seen a bundle on the floor with feet
sticking out and that she never saw a face, but at trial she
testified that that was a mistake she had made because she
was nervous when speaking with the officer.
40 In her grand jury testimony on May 27, 2008, Narcisa
testified that defendant had covered Guadalupe's body so
her feet, but not her face, were visible. At trial, Narcisa
did not recall her grand jury testimony, because "it was
so long ago, " but she explained that she had meant to
say that Guadalupe's feet were visible when defendant
placed her in the truck and that she saw Guadalupe's
41 Maria testified that in the summer of 1990 she and Roberto
were living with their children on the horse farm. Maria
recalled a Sunday in July 1990 when defendant and Narcisa
came to their house. Maria was pregnant at the time, and
Narcisa recently had given her a baby shower. Maria regarded
Narcisa as a mother to her. Narcisa usually greeted Maria
with a hug and kiss, but that day Narcisa was quiet and cold.
Maria asked Narcisa if she was feeling well or if she wanted
to go inside to watch television and have a glass of water.
Narcisa agreed and went inside with Maria. Defendant did not
go inside, but, otherwise, Maria did not know where he went.
Maria and Narcisa watched television for a few hours. Late at
night, defendant returned, and he left with Narcisa.
42 Maria remembered the visit because, although Narcisa and
defendant often visited her separately, it was unusual for
them to come to the house together. It was also unusual for
defendant to visit without calling or making plans in
advance. While Narcisa was in the house, Roberto came in a
couple of times and spoke with them briefly before returning
to work in the barn. Narcisa told Maria that she was not
feeling well, which was uncharacteristic of her.
43 Roberto testified that his father, Juan, died in 2009. In
the first half of 1990, Roberto did not see Guadalupe very
often, though Maria would occasionally babysit Maribel.
Roberto, Juan, and ...