For the second time in a year, police in Wisconsin are investigating the sexual assault of a horse after a bizarre incident Sunday.

A farmer near New London called Waupaca County authorities after noticing his horses appeared to be spooked, according to authorities. The 5-year-old, pregnant mare was bleeding and injured, and a veterinarian later determined that the horse was molested.

“I think that an instrument, some sort of hobbling device, was used on the horse,” Waupaca County Sheriff Brad Hardel said. “It is disturbing, for sure."

“It is disturbing, for sure."

- Waupaca County Sheriff Brad Hardel

Hardel told FoxNews.com his department contacted a person of interest with a record of sexually assaulting horses, but that person "was on the verge of being exonerated," said Hardel.

The horse's owner believes the assault occurred Saturday night or early Sunday morning as the horse was acting normal late Saturday afternoon, Hardel said.

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Last Dec. 17, Jared Kreft, 31, of Wausau County, was charged with bestiality after allegedly performing a sex act with a horse in Marathon County. Kreft, 31, was charged with sexual gratification with an animal sex organ, possession of drug paraphernalia, possession of marijuana as a repeat offender and bail jumping, according to court records.

Police said they caught Kreft in a barn wearing a face mask, black jacket and blue wind pants with holes cut in the groin and buttocks areas, according to court documents.

He later told deputies he performed oral sex on the horse after viewing "horse pornography." Kreft pleaded guilty to possession of marijuana under an agreement in which charges of bestiality and disorderly conduct were dismissed.

Kreft said Tuesday that he knew nothing about Sunday’s incident and that having sex with horses “is not in my character.”

Hardel said his detectives were aware of other incidents involving sexual assaults of horses and would be looking at other possible suspects, including Kreft.

"We are aware of that subject, also," Hardel said. "We will be talking to a number of people. This is a malicious crime. We need to find this person and get them off the street as quickly as possible."