Investigators with Orange County’s animal care agency say they have located a person believed to be the owner of a dog that attacked three horses and a rider in O’Neill Regional Park last month.

OC Animal Care had been seeking the identity of the dog’s owner since the March 27 attack. The name of the owner and the dog’s whereabouts won’t be made public until an investigation is complete, said Jennifer Hawkins, the agency’s chief veterinarian and interim director.

“We are grateful to the local communities that responded to our pleas for information,” Hawkins said. “This information has led us to a person we believe to be the dog owner.”

Officials say the owner was identified from a picture taken by Helga Thordarson, after her rare Icelandic horse Tyr was among three horses and a rider attacked during an outing on Live Oak Trail at the Trabuco Canyon wilderness park.

Thordarson posted the picture on her Facebook timeline following the attack as a heads-up for her friends and neighbors who ride at O’Neill.

The photo has more than 1 million views after it was shared from her timeline by a fellow Facebook user.

“The story and photo obviously struck some kind of chord,” she said. “We continue to receive messages of support, as well as lots of unsolicited assistance in the search for this dog owner.”

“Social media was unequivocally helpful and – while I was taken by surprise and astonished at the magnitude and passion of the public response – we are immensely grateful for all the help we have received,” Thordarson added.

Tyr escaped the dog – described as an off-leash white and brown-boxer-mix – but the dog chased the 15-year-old gelding to the bottom of the trail.

Thordarson followed and caught up with her horse. Once reunited, four women hiking with the suspected dog came toward her. She asked for the owner’s contact information; when a woman refused to provide it, she snapped a picture of the group.

The attack left two of the three horses wounded and put rider Sandie Weaver of San Juan Capistrano in the hospital. Weaver is on the mend but Oska, her 22-year-old mare is looking at a lengthier recovery. She sustained deep tissue damage which in some cases are life threatening said Paul Wan, a equine veterinarian at Equine Veterinary Specialists in Norco. He is treating the horse.

“There are vital structures on horses legs that can be damaged,” he said. “Sometimes we have to put those horses down because they become lame.”

Thordarson has been back on the same trail with Tyr. She encountered several dogs but the horse hasn’t shown any trauma following the attack.

“He’s been well-adjusted since then,” Thordarson said. “That’s not something one would expect given the severity of the attack.”

Thordarson said she noticed an improvement in dogs being on leashes in areas of the park where they’re allowed. She’s also noticed better cooperation among equestrians, hikers and bikers.

Contact the writer: eritchie@ocregister.com or twitter:@lagunaini