You've already admitted you're biased due to having friends and family in a police department in the area, so it's hard to take your opinion as anything but blatant bias.
They have a procedure to follow. They didn't follow it. They botched the investigation.
Gallagher calling it ok on the stand doesn't make it ok.
Being a cop for 30 years doesn't make it ok to ruin a homicide investigation out of pure unprofessionalism + apathy + who knows what else. Lots of veteran cops do irrational things, awful things, you name it.
All the cover-up issues regarding Karen & Jen McCabe are clearly more than enough, then you add in this clown with his red solo cups and other garbage. The station was 1 or 2 miles away. He freely admitted on the stand he could've gotten the appropriate tools but didn't. He sent an officer to their own house to get a damn leaf blower but couldn't go to the station for swabs, containers, evidence bags. It makes no sense.