Former Michigan State University medical student Andrew Thompson pleaded guilty to felony animal killing Monday morning, ending a case animal control officers call one of the most heinous they've ever seen.

Thompson is accused of killing 13 Italian Greyhounds and injuring another, but in a plea deal will only be sentenced for killing 11 dogs. Under that deal, he is now convicted of three felonies.

After nearly a year of fighting the disturbing allegations, 24-year-old Thompson took just minutes to explain himself in court.

"I got upset, I hit the dog and it died," Thompson told an Ingham County Judge, as he described how one of the killings happened.

Prosecutors say he threw the tiny dogs against a wall, hit them and grabbed them by the neck.

"I think the effort that was put into aquiring each animal only to end up dead is just mind boggling," Jamie McAloon Lampman, with Ingham County Animal Control said. "That whole process, bringing them in from out of state, spending all that money, going to the airport to pick them up, bringing them back."

Officers found the dog who survived in a closet, malnourished and clinging to life.

"She was bruised with obvious signs of trauma, she was bleeding and most likely bleeding internally," Dr. Joyce Heideman, with Southside Animal Hospital said.

Heideman says it was touch and go for days, but she was able to nurse the dog she calls Jezabelle back to health. The veterinarian has now adopted her.

Heideman is glad to see Thompson convicted and hopes what happened to Jezabelle will never be repeated.

"Before we got to 13 this could have been stopped at dog number one, number two, number three," McAloon Lampman said. "I mean there were people that knew this was going on."

While Jezabelle may be the lucky one, Heideman feels lucky too. The love between savior and survivor, she says is stronger than cruelty can ever be.

Thompson and his attorney had no comment after court. The 24-year-old will remain free on bond until he is sentenced in June.

He faces up to four years in prison and a $5,000 fine for each of the 11 dogs killed.