LAS VEGAS -- Boulder City police say they're investigating the drugs used at the shelter and have formally filed for charges against the former animal control supervisor accused of improperly euthanizing more than 100 animals.
Mary Jo Frazier has been accused of violating the city code requiring a five-day waiting period and veterinarian review before an animal is killed.
She couldn't be reached for comment.
Darla and Robert Kissel say they recently learned their dog Whisky was unlawfully killed in 2006, CBS affiliate KLAS reports.
"I just want justice for my animal. It still hurts," Darla said. "It's horrendous. It's horrible. I can't even imagine."
The Kissels, other dog owners, and concerned Boulder City residents addressed the Boulder City Council Tuesday night.
"Think about what we've all gone through because of this woman," said Margaret Hance whose dog was also killed.
An investigation in April revealed Frazier illegally killed 91 animals. Instead of pushing the case forward, the head of the police department, Bill Conger -- who oversees Animal Control -- brought in a new shelter manager.
Frazier was allowed to retire, but he Clark County District Attorney's office said its screening team is reviewing the case submitted Thursday by the city before a decision is made to prosecute.
City officials couldn't immediately be reached for comment Friday.
This week, it released a letter to the district attorney dated Dec. 10 that indicated police would also investigate "potential chain of custody issues associated with pharmaceuticals used at the animal shelter."