Detectives have revealed that a San Diego-area man under suspicion in the deaths of his wife and mother-in-law was arrested Thursday on sexual assault charges.

It has been reported that Michael Richardson, 37, of Chula Vista, was picked up by San Diego County sheriff's investigators on charges he sexually assaulted the 17-year-old niece of his wife. Richardson's wife and her mother were found dead in a wrecked car this week.

Richardson, who had been called a person of interest in the death investigation, refused to speak to reporters as he was led away from his home following his arrest, KGTV-TV, San Diego, has said.

It has also been reported that the bodies of Thao Richardson, and her 72-year-old mother, Than Lyi, were found Tuesday outside a wrecked car in a ravine in remote area of the county east of San Diego. Investigators quickly grew suspicious that the crash had been staged and that the two women had been the victims of a homicide.

The reports further noted that it was later learned that Richardson had been arrested in March for allegedly having a sexual relationship with the teenager, but no formal charges were filed after the teen refused to cooperate with prosecutors. (With Inputs from Agencies)