MADISON, Wis. -- Madison police are reinvestigating the case of a mother who disappeared nearly 30 years ago.

Authorities are re-examining the circumstances surrounding the woman's disappearance and they said that they suspect foul play, WISC-TV reported.

The disappearance of Jean Zapata left her three children in limbo. The renewed interest in her case has cast a spotlight on her once-estranged husband.

Authorities said that Eugene Zapata is their one and only suspect.

Police said that they believe Jean Zapata is dead, but don't say the mother and flight instructor was murdered.

Search warrants released on Thursday indicate that detectives have been searching for human remains since last year, WISC-TV reported.

Last December, at Zapata's former East Side house, two cadaver dogs identified decomposing human remains in a crawl space in the basement. Later, a human hair was found.

Last August, two dogs also identified the presence of human remains at a storage locker rented by Eugene Zapata.

Warrants said that Eugene Zapata turned in his locker key the day after Madison police rang his Nevada home to question him.

"We believe he was involved in the disappearance, and we believe he's a suspect in that," said Capt. Tom Snyder of Madison police's Criminal Intelligence Unit. "Obviously, we have to follow every investigative lead that comes in regarding this case."

Jean Zapata was in the middle of a divorce and had a temporary restraining order against Eugene Zapata when she disappeared without a trace in 1976, WISC-TV reported.

In August, a search of some Juneau County land owned by Eugene Zapata turned up nothing.

WISC-TV was unable to reach Eugene Zapata by phone.

Authorities said that anyone with information is urged to call Crimestoppers at (608) 266-6014.