United States District Court, M.D. Pennsylvania
Christopher C. Conner, Chief Judge.
April 2018, this court resolved a motion to suppress filed by
defendants Xiao Wu Zhou (“Zhou”) and Chuanze Xu
(“Xu”). We held that (1) Pennsylvania State
Police Trooper Jeremy Hoy (“Trooper Hoy”) had
reasonable suspicion that defendants committed a traffic
violation which justified initiating a traffic stop on
October 31, 2017, and (2) Trooper Hoy then developed
reasonable suspicion that defendants were engaged in criminal
activity sufficient to extend the duration of that stop and
request a canine unit for a dog sniff. Zhou now moves to
suppress evidence obtained during that traffic stop based on
the alleged impropriety of the dog sniff. (Doc. 72). The
court will deny Zhou's motion.
Findings of Fact 
evidence adduced during the July 19, 2019 evidentiary hearing
falls into three categories: fact witness testimony and
documentary evidence concerning canine training and
procedures; fact witness testimony and documentary evidence
regarding the dog sniff conducted during the October 31, 2017
traffic stop; and expert testimony on the issues of natural
and trained canine behavior.
Canine Training and Procedures
2011, the Pennsylvania State Police acquired a one-year-old
Belgian Malinois named Tom (“Canine Tom”). (Tr.
9:10-15, 21:20-21). Trooper Aaron Tiracorda (“Trooper
Tiracorda”) was assigned as Canine Tom's handler,
the two began a 12-week basic training course for narcotics
detection in May 2011. (Id. at 8:5-13, 8:24-9:4,
9:13-15, 10:7-10, 11:11-14). Handlers train with their
canines in “real-life settings”-e.g.,
buildings and automobiles-using real narcotics, known as
“training aids” or “finds.”
(Id. at 10:11-11:10). Trooper Tiracorda and Canine
Tom completed the 12-week course on July 22, 2011.
(Id. at 9:13-15). Canine Tom was trained to detect
heroin, methamphetamine, marijuana, and cocaine. (Gov't
Ex. 4 at 7; Tr. 16:19-23).
teams “must certify annually, ” attend monthly
in-service training sessions, and train a minimum of four
hours per week. (Gov't Ex. 11 at 2-3; Tr. 9:16-10:6).
Trooper Tiracorda and Canine Tom were most recently certified
by the Pennsylvania State Police on October 3, 2017, and
October 3, 2018. (Gov't Ex. 6; Gov't Ex. 7; Gov't
Ex. 10 at 77). In the ten months preceding the October 31,
2017 traffic stop, Canine Tom located 85 of 89 hidden finds
resulting in a 95.5% success rate. (Gov't Ex. 9 at 1, 12,
17, 22, 31, 35, 43, 50, 54, 59).
canine team proceeds in several steps when responding to a
request for an exterior search of a vehicle. Upon arriving at
a scene, the handler walks around the vehicle to identify any
potential hazards to the canine. (Tr. 20:24-21:9). The
handler and canine then engage in a “fast pass”
search pattern which involves a systematic search of the
vehicle in one direction and then a reverse of that search.
(See id. at 36:5-18, 53:5-7). Typically, the handler
will commence the search pattern by commanding the canine to
“find it.” (Id. at 53:2-4).
Tiracorda defined Canine Tom's alert behavior as “a
sudden change in posture [and] an increased respiration when
the dog first encounters the odors he's trained to
detect.” (Id. at 14:19-23). Alert behavior
cannot be trained; it is a “natural reaction to
stimuli.” (Id. at 14:24-15:2). When a canine
exhibits alert behavior, the handler conducts a
“two-meter rule” exercise. (Id. at
15:3-6). The handler will “detail” a two-meter
area near the location where the canine began to alert by
“cast[ing] productive areas” where contraband may
be found. (Id. at 15:3-15). A handler casts by using
the back of a hand, without patting a particular location, to
lead the dog to smell within the two-meter area.
(Id. at 15:15-17).
canine is taught to pinpoint the source of the odor first
alerted to by exhibiting trained indication behavior.
(Id. at 16:2-7). Canine Tom was trained to passively
indicate the position of narcotics by locking, pointing, and
staring at the location. (Id. at 15:23-16:1,
16:15-18, 16:24-17:12, 44:12-15, 55:21-23). Trooper Tiracorda
explained that Canine Tom was also trained to sit as part of
his indication behavior. (Id. at 16:24-17:6,
29:13-16, 44:12-15). Trooper Tiracorda described sitting as
the preferred posture that accompanies the locking, pointing,
and staring. (Id. at 37:5-8, 44:14-15, 48:22-24,
55:21-24). When the source of an odor is low to the ground,
Canine Tom will sometimes lie down rather than sit.
(Id. at 17:7-8, 44:12-15). And Trooper Tiracorda
noted that Canine Tom sometimes stands rather than sits when
exhibiting the lock, point, and stare indication.
(Id. at 17:6-7, 29:13-30:4).
Tom is trained to associate the odor of narcotics with
finding a toy. (See id. at 17:23-25, 70:5-6). When
Canine Tom locates narcotics, he is rewarded with various
toy-like items. (Id. at 25:20-24). Canine Tom
will not stop staring and will not leave the location of a
find until he receives a reward. (See id. at
17:22-18:1, 55:24-56:3, 72:8-11). To remove Canine Tom from a
find location in the field without rewarding him (for
example, in the event of a false indication), Trooper
Tiracorda will conduct a “praise off.” (See
id. at 17:13-18:5, 72:15-24). A praise off involves
verbally encouraging or praising Canine Tom for following his
training and physically removing him from the location.
(Id. at 18:5-7, 25:16-19, 70:2-3, 72:8-11). The
praise off is designed to balance two competing goals: (1) to
remove Canine Tom from the scene without correcting him
(e.g., with a leash tug) for what is likely a
successful find and (2) to avoid prematurely rewarding Canine
Tom before confirming drugs are present. (See id. at
18:8-10, 25:11-19, 70:12-71:5, 71:12-18, 72:8-24). Once
Trooper Tiracorda confirms the presence of drugs, Canine Tom
receives a toy reward as positive reinforcement.
(Id. at 70:3-4, 71:12-15, 72:15-17).
Dog Sniff of the U-Haul Truck
October 31, 2017, Trooper Tiracorda responded to Trooper
Hoy's request for a canine unit on the eastbound side of
Interstate 80 near mile marker 159. Zhou, 2018 WL
1858187, at *2; (Tr. 12:16-13:3). Trooper Tiracorda canvassed
the exterior of the U-Haul truck looking for anything that
could harm Canine Tom. (Tr. 20:24-21:9; Gov't Ex. 1 at
15:11:00-15:11:45). After determining that the wind was
blowing west to east, Trooper Tiracorda decided to begin the
canine search at the front of the vehicle to “use the
wind to bring any odors . . . to the dog.” (Tr.
13:15-14:1). As Trooper Tiracorda moved Canine Tom downwind
toward the front of the U-Haul truck to begin a search
pattern, Canine Tom suddenly stopped and snapped his neck and
body back toward the rear wheel well on the passenger side of
the truck. (Id. at 14:2-12, 22:22-23:6; Gov't
Ex. 1 at 15:14:55-15:15:07). Canine Tom then began closing
his mouth and exhibited “increased shallow
respirations.” (Gov't Ex. 4 at 7; Tr. 14:19-23).
Tiracorda observed Canine Tom's alert behavior and
immediately detailed the area by casting his hand along the
bottom rail of the U-Haul truck's cargo box near the rear
wheel well. (Tr. 15:18-22, 22:2-11, 23:2-14; Gov't Ex. 4
at 7; Gov't Ex. 1 at 15:15:05-15:15:15). He held the
leash loose to allow Canine Tom room to maneuver. (Tr.
23:13-21; Gov't Ex. 1 at 15:15:05-15:15:15). Canine Tom
paced back and forth in shorter and shorter distances as he
narrowed down the source of the odor. (Tr. 24:3-9; Gov't
Ex. 1 at 15:15:15-15:15:25). Canine Tom then locked onto the
rear corner of the cargo area on the passenger side, froze in
place, and indicated by standing, pointing his head and nose
out, staring, and wagging his tail. (Tr. 15:23-16:1,
16:10-18, 24:12-16; Gov't Ex. 1 at 15:15:23-15:15:33).
Although Trooper Hoy briefly stepped in between the dashboard
camera and Canine Tom, Canine Tom's indication behavior
is clearly visible both before and after Trooper Hoy
obstructs the camera's view. (See Gov't Ex. 1 at
15:15:25-15:15:35). Trooper Tiracorda continued moving back
and forth for a few moments, but Canine Tom remained frozen