FAIRFAX, Calif. >> Detectives say they are looking for three persons of interest in the killing of a man on a Northern California hiking trail.

Marin County sheriff’s investigators on Tuesday evening released surveillance video that shows two of the three people they want to question in the shooting death of 67-year-old Steve Carter.

The surveillance footage taken from a convenience store in Fairfax shows a long-haired man wearing a black hat and a woman with dirty-blond hair, wearing dark clothing.

Carter’s body was found by a hiker 6 p.m. Monday along a scenic trial about 20 miles north of San Francisco, the Marin County Sheriff’s Department said. He was still holding onto the leash of a Doberman Pinscher believed to be his dog, Lt. Doug Pittman said. The dog was also shot, but it survived and was turned over to the Marin Humane Society, Pittman said.

Pittman identified the victim as Steve Carter.

Carter’s brother, Michael Carter, told the San Francisco Chronicle: “I’ve heard that he was murdered, but I haven’t heard anything other than that.”

Carter said that he knew of no one who disliked his brother. “I can’t imagine that it’s anything other than a random thing. All of it seems very random and unbelievable. Nothing makes any sense.”

Carter and his wife, Lokita Carter, founded the Ecstatic Living Institute, based in Middletown. He was a Tantra teacher and participated in numerous training sessions across the country and in Canada and Costa Rica. The couple released DVDs on Tantric massage, yoga for lovers and meditation. They also taught classes at Harbin Hot Springs, a clothing-optional retreat in the Middletown mountains that burned down last month in Lake County’s devastating wildfire, the Chronicle reported.

Logan Rose, director of the Ecstatic Living Institute, said the Carters recently led retreats for couples in Costa Rica and had come to Marin County so Lokita could undergo treatment for breast cancer.

“It has been a very traumatic season for us with Lokita’s cancer, then the Valley Fire that destroyed our beloved Harbin Hot Springs where we offered the majority of our workshops,” Rose said. “This is the most devastating blow. We are heartbroken.”

The victim is believed to have driven to the trail near Fairfax, California, in his silver 2003 Volkswagen Jetta station wagon, Pittman said. The car was missing and believed to have been stolen by the killer.

Anyone who spots the car should treat the occupants as armed and dangerous, Pittman said.