The discovery of a man's body under a freeway bridge near San Diego Wednesday led police to a home where they found the bodies of a woman and two children, prompting investigators to probe the deaths as a possible murder-suicide, officials said.

The investigation began early in the day after the man's body was spotted about 150 feet below a bridge near an abandoned car that was partially blocking traffic on an eastern San Diego County freeway, Chula Vista police spokesman Bernard Gonzales said.

Officers investigating the vehicle decided they needed to check on the welfare of its owner and tracked her to the Chula Vista home where the bodies of Mary Alvarez, 41, Angelica Alvarez, 12, and Hamid Alvarez, 11, were found, Gonzales said.

He offered no details about the causes of the death.

Police Capt. Gary Wedge said Mary Alvarez was a teaching assistant at San Ysidro High School in San Diego County, and that she had not reported to work for several days.

Alvarez was the children's mother, but the still-unidentified man who apparently jumped to his death was not their biological father, Gonzales said.

He and Alvarez are believed to have at some point been in a romantic relationship and he had lived in the Chula Vista home until recently, Gonzales said.

Karin Mendoza, a neighbor in the newly constructed subdivision of tile-roofed, Spanish-style condo buildings and townhouses where the bodies were found, said she had seen a man, woman and two children entering and leaving the home.

Mendoza said the neighbors kept to themselves in the home, and she saw no sign of trouble.

"They were very serious, but I never heard anything," she said.

The murder-suicide investigation came less than a week after a separate incident in San Diego County in which a couple is suspected of carrying out their own deaths and those of their two daughters. Their bodies were found in a swimming pool and bathtub of their home.