Police revealed Wednesday who they found responsible for the murder of a pregnant grocery store cashier from Santa Cruz County.

Police have arrested Michael McClish, a manager at the market where Joanna “Asha” Veil, the cashier, worked. He is the only person ever publicly named a suspect in the 2006 death of Veil, who was seven months pregnant.

McClish, 38, is already in prison, serving a life sentence for raping and threatening another woman he had a relationship with.

“In our lengthy investigation we have found that Michael McClish had both a motive and an opportunity to commit these murders. Asha and McClish had both a professional and a personal relationship,” investigators told ABC News.

Veil was a cashier at the Ben Lemond Market, where McClish was a manager. She was last seen leaving work Sept. 9 about 7:30 p.m. and reportedly met with McClish just before her disappearance, but McClish later invented an alibi to cover up their meeting.

Veil was reported missing on Sept.12, and her body was found two days later. Investigations revealed she had been strangled and bludgeoned to death.

"Today is a crucial step," Sheriff Steve Robbins said of the man’s arrest. "The sheriff's office knows that her family, friends, co-workers and the San Lorenzo Valley community as a whole have been deeply affected by these tragic deaths."

Lt. Phil Wowak said Wednesday that McClish and Veil had both a professional and personal relationship, but sheriff’s officials said the father of Veil’s baby was her estranged husband, Richard Veil of Santa Cruz.