MADISON, Wis. -- A 30-year-old disappearance case has now turned into a homicide investigation.

Authorities call it the ultimate cold case.

Jean Zapata, 36, disappeared without a trace in 1976.

She sent her three young children off to school and was never seen or heard from again.

"She would not abandon those children and go wandering off," said Zapata's friend Peg Weekley.

Weekley, a longtime friend of Zapata's, who now lives in Oklahoma, recently convinced some new detectives to take a second look at the case.

"I thought the children deserved to know the truth of what happened to her if at all possible," said Weekley.

Now Zapata's children may finally get some closure, though not the kind anyone had hoped for.

"I believe she was murdered," said Capt. Tom Snyder.

The case was once labeled a disappearance, but is now a homicide investigation and Zapata's former husband, Eugene, is the one and only suspect.

"She was in the midst of a messy divorce with her husband Eugene Zapata at the time," said Snyder. "There was a restraining order against him. They were going through a custody battle regarding their children."

It was Jean's boss who first reported her missing, two days after she failed to report to work as Madison's only female flight instructor.

Eugene was then caring for the children.

At the time, police searched the home and found Jean's purse, coat, clothes and new car as well as other red flags.

Eugene became a suspect back then, too after giving police conflicting alibis about the day she disappeared.

Investigators learned the former state transportation worker also argued with his wife about visitation rights a few days before she disappeared and had hired a private detective to follow her a month before that.

"Until she told me why she was divorcing him, I didn't realize that he wasn't the man I thought he was," said Weekley."

Weekley told News 3 that Jean had confided in her that Eugene had secretly put semi-nude pictures of her in swinger magazines.

Zapata accidentally found out when a call from the postmaster led her to a secret post office box and ultimately her own face.

"And there were these swinger magazines and she opened one up and there was a picture of her scantily clad that he had taken," said Weekley."

Eugene Zapata, 68, now lives with his second wife in Henderson, Nev.

News 3 found that is where Madison detectives executed search warrants in December.

The search warrants covered Eugene's house, computer, a bank safe deposit box and a sample of his DNA.

"We are very hopeful that there will be a prosecution in this case, hopefully in the near future," said Snyder.

Snyder said he believes it will happen despite the lack of a body.

Officers used two trained cadaver dogs to sniff out some new evidence in the case.

Inside the former Zapata home, police say the dogs were able to detect human remains.

"In a crawl space in the basement two independent searches by cadaver dogs found or indicated the presence of decomposing or decomposed human remains," said Snyder.

Authorities also say cadaver dogs also detected human remains inside and outside a Sun Prairie storage locker rented by Eugene Zapata from 2001 until last April.

He cleaned it out one day after police contacted him asking about Zapata's disappearance.

So far, the new police investigation has yet to produce charges or even prove Zapata is dead.

News 3 spoke with two of Zapata's children who say they have now accepted that.

Zapata's youngest daughter told News 3, "Although it is a gift to know my mother didn't abandon my brother, sister and me, it is devastating to now know that she has been dead all these years. My greatest hope is to recover her remains for a long-overdue memorial service. I need to honor her memory and grieve her loss, again."

News 3 talked to Eugene Zapata who denied all allegations that he was ever involved in Jean's disappearance. He said he is not at liberty to discuss the case on the advice of his Madison attorney, Stephen Hurley.

Hurely did not return calls or e-mails from WISC-TV.