Respectfully BBM, could be many reasons we are unaware of. Reasoning I posted was jmho but from all we know of the K9 used at Creekside Church of Christ ... from media and ATF webpage:
"...One federal agency confirmed Wednesday night theyre assisting in the case.
The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) local bomb sniffing dog Titan and his Agent have searched the building and grounds of the church. Some clues Titan could hit on are cast off gun casings and gun residue. Officials didnt say whether or not the dog provided any breaks in the case. ..."
http://dfw.cbslocal.com/2016/04/20/creekside-churchs-exterior-cameras-off-day-of-midlothian-murder/
Name: Titan
Specialty: Explosives Detection
Breed: Labrador Retriever
Color: Yellow
Sex: Male
Weight: 73 pounds
Birthday: May 2, 2012
Training: ATF National Canine Center, Front Royal, VA.
Handler: Special Agent Canine Handler Daniel Kaase
Location: Dallas Field Division
K-9 Titan is one of four new graduates from ATFs Search Enhanced Evidence K-9 (S.E.E.K) program and is a trained Explosives Detection Canine (EDC). He came to ATF from a local vendor at 22 months old. K-9 Titan is a very large Labrador, so his name suits him well. He has the ability to be sent off-leash to specific targets such as vehicles or luggage, up to 150 meters. Once at the target, he can be directed using hand and whistle signals to search for explosives and/or firearms. If K-9 Titan detects explosives and/or firearms he will alert his handler by sitting. By sending him down range, this provides the handler with an extra level of safety by allowing the handler to be at distance away from the target being searched.
Titan is all work and excels in open environments searching for explosive-related materials to include firearms, ammunition shell casings and explosives. Although he is large in stature, Titan leaves no small spaces unsearched. Titans operational home working area is the entire state of Oklahoma, North and West Texas up to the New Mexico border. When called upon, Titan always responds to the situation and is eager to serve.
K-9 Titan came to ATF from the state of Washington. He currently lives in North Texas just outside of Fort Worth with its large expanse of countryside. Titan feels right at home, because he is very rambunctious and loves to run.
https://www.atf.gov/about/k9/titan