Andres Lopez Elorez, a veterinarian in training, was arrested and sentenced to six years in prison for stitching liquid heroin into the puppies’ stomachs as a way to import the drug, Thursday at the Federal District Court in Brooklyn.

Alicia N. Washington, a prosecutor of the case, told the court that law enforcement officials have found some of the puppies already filled with heroin, while others are already being prepared for surgery.

The dogs that were found alive were adopted into new homes, including one Rottweiler, who now serves as a drug detection dog for the Colombian national police, while a beagle was adopted by a police officer, according to the Drug Enforcement Administration.

Sadly, three puppies were pronounced dead after contracting viruses during the emergency operations, according to a report by The New York Times.

Elorez’ court-appointed attorney, Mitchell Dinnerstein, told the court of another veterinarian who mentored Elorez into making the “puppy project,” and still has not been arrested despite its ties with drug traffickers.