An Iowa Court of Appeals ruling tossed out the animal torture conviction of a man who was accused of beating his puppy to death with a baseball bat.

A panel of three judges ruled 2-1 on Wednesday to overturn the 2012 conviction of Zachary Meerdink, on grounds that prosecutors had failed to prove "depraved or sadistic intent" when he killed the puppy.

Meerdink, 31, bludgeoned his 7-month-old Boston Terrier in December 2011 after it became aggressive, having accidents on the floor and biting his girlfriend's children who lived in the home, court documents allege.

"After considering the definitions of 'depraved,' we conclude 'depraved intent to cause death' does not equal an 'intent to cause death,'" the court ruled.

"Here, the State proved Meerdink killed the dog; however, no one saw Meerdink kill the dog, and no testimony or exhibits and no reasonable inferences or presumptions from the testimony and exhibits sufficiently prove Meerdink acted with a depraved intent to cause death," the ruling continued.

In December 2011, Meerdink's girlfriend, Jamie Holladay, testified she was running an errand with her children when she received a call from Meerdink, asking her where he could find disinfectant since the puppy had another accident, according to court documents.

When Holladay returned home, she said Meerdink had a blank look on his face and was unresponsive as he walked to the front door of their apartment with the dog under his arm, according to court documents.

A few minutes later, court documents allege Meerdink returned carrying a baseball bat.

"He didn't say anything," Holladay testified. "I asked him where the dog was and he just told me that the dog was dead."

A police officer responding to a call from Holladay found the puppy in tall grass , with a pool of blood about ten feet away, according to court documents.

Meerdink has been free on parole since April 8, according to the Des Moines Register.

He was not immediately able to be reached for comment.

Tom Colvin, executive director of the Animal Rescue League in Iowa, told ABCNews.com the case is a "perfect example that there needs to be a close scrutiny of our animal protection laws."

"It's very disturbing to us," Colvin said. "We certainly would think taking a puppy and a baseball bat and beating it to death certainly sounds depraved to me and many others who hear about this case. It's quite alarming."