(10-11) 00:01 PDT Oakland, Calif. (AP) --
The estranged husband of a missing mother was arrested on suspicion of murder in connection with her disappearance more than a month ago, police said.
Hans Thomas Reiser was arrested one day after Oakland police, with the help of the FBI, searched his house a second time for clues in the disappearance of Nina Reiser.
Nina Reiser, 31, was last seen Sept. 3 while dropping off her 7-year-old son and 5-year-old daughter at her husband's home in the Oakland hills. She never showed up for a meeting with her best friend that evening. Her Honda minivan was found Sept. 9 with her purse and groceries still inside.
Deputy Chief Howard Jordan said on Tuesday that even though police are still looking for Nina Reiser's body they decided to charge Hans Reiser based on biological evidence and statements from friends and relatives of the missing woman.
"Our investigation has gone from a search and rescue to a search and recover," Jordan said at a news conference.
The Reisers have been embroiled in an acrimonious divorce and child custody fight after separating in May 2004. Nina Reiser filed for divorce three months later, but it has not been finalized.
Jordan said Hans Reiser has remained under surveillance for several weeks.
Hans Reiser, who is expected to be charged this week, has refused to speak to authorities. His lawyer, William DuBois, did not immediately return a call Tuesday.
Nina "Nenasha" Reiser moved to the U.S. in 1999 from St. Petersburg, Russia where she worked as a medical doctor. Her mother, who still lives in St. Petersburg, said she talked to her daughter the day she disappeared. She said Hans Reiser has ignored her attempts to speak with him.
The two children remain in protective custody. Their father has tried to convince authorities they should be reunited with him.
Even though Nina Reiser's body has not been found, police believe she is dead and enough circumstantial evidence exists to allow for Hans Reiser to be prosecuted.
Police told the Oakland Tribune biological evidence that puts the missing woman in a car her husband had access to is a strong part of the circumstantial case against him. They would not say what the biological evidence is, but the term usually includes blood, hair or other body fluids.
The link to the car is important because Nina Reiser's friends have told authorities she would never had voluntarily ridden in a car with him.
Last month, police obtained a search warrant to secure a DNA sample from Hans Reiser.
A $15,000 reward was offered for information about the missing woman.