CHESTER COUNTY — Chester County Sheriff Alex Underwood was devastated on Tuesday night after he said someone poisoned his dog.

The incident occurred just weeks after he took office.

The 19-month-old German shepherd, A.J., was becoming pretty popular in Chester County, especially at local schools.

"The kids loved him. We always took him around to different places," Underwood said.

Underwood was the proud owner of the loyal dog he was training to become a K-9 at the department, but now he said A.J. will no longer have that chance due to a crime Underwood said he just can't understand.

"It's like taking a child, he didn't bother anybody," said Underwood.

He said he believes someone poisoned his dog late this weekend.

"This past Sunday when we were at the Martin Luther King parade here in Chester, we let him out in the yard just to play around until we got back," said Underwood.

Shortly after Underwood returned he said A.J. was acting oddly.

"He was actually foaming from the mouth, and stuff like that, and he eventually died right before daylight," said Underwood.

Underwood was recently sworn in as the first-ever African American sheriff in Chester County. He said A.J. was quickly becoming part of the team.

"Everybody knew him, I mean he was here. He'd be in 911, sometimes he'd be in my office, sometimes he'd be back in narcotics, he was just kind of, he was part of the family here," said Underwood.

He said they do have possible suspects, but he wouldn't elaborate.

Underwood only said these acts will not be tolerated.

"This is a criminal act, and anybody breaking the law in Chester, they better realize one thing definite, its going to stop, because we going put them in jail," said Underwood.