NAPA, Calif. -- A $4,000 reward is being offered for information leading to the arrest of person responsible for two separate poisonings of six dogs in Napa over the last few weeks -- including a police canine at an officer's home -- that have left four animals dead.

Police Sgt. Michael Hensley said the three dogs were found around 11 a.m. Nov. 3 at police officer Ryan Cole's home showing signs of poisoning. Officer Cole said wasn't sure he would be able to hit the streets of Napa again with his K-9 partner Rex. The 8-year-old Czech shepherd came very close to dying after a nasty encounter with a highly toxic pesticide.

"Besides losing a vital part of my immediate family, the Napa police department would have lost a very valuable resource and tool," said Officer Cole. "And it would have been devastating."

It was Cole's wife who found Rex and the family's two pet German shepherds convulsing in the backyard. Napa police say someone intentionally threw a box of snail bait over the Cole's fence, which the three dogs devoured. For one of the dogs, the poison had deadly results.

"By the time we had gotten to the vet, I had lost Lily," said Officer Cole. "They had worked on Ruby and Rex for 6 hours until Ruby and him were both stable."

The malicious poisoning came just a few days after a homeowner in the browns valley area found her three dogs dead in the backyard. Again, a box of snail bait was discovered.

Police say that incident on October 29th is similiar to what happened to Officer Cole's dogs. Authorities don't consider either a prank, calling the incidents cowardly crimes.

"We're pursuing this [as a] full felony case:.torture to animals. Four animals … were killed and we're taking it very seriously," said Napa police detective Mike Walund.

A reward of $4,000 that came from donations is being offered for information leading to the arrest and conviction of the person or persons responsible, Hensley said. Those responsible are looking at hefty fines and state prison, on cruelty to animal charges as well as intentionally injuring a police dog.

Anyone with information can call the Napa Police Department at (707) 257-9223 and ask for the investigations bureau.