D.C. boy, 6, missing; Guilty plea in D.C. stabbing; Child porn conviction in Va.

He said authorities think that the suspect and the victim knew each other. Neither was identified.

The suspect was described as a 27-year-old Hispanic man with light skin, short cropped black hair and brown eyes. He was last seen wearing bluejeans and a gray sweater with the lettering "ECKO" on the front.

Anyone who observes any suspicious activity in that area is asked to call the Sheriff's Office at 703-777-1021.

-- Martin Weil

Man claims insanity

A man accused of fatally shooting a cabdriver in Tysons Corner is claiming he was insane at the time and will have one of the country's top psychologists in criminal behavior testify on his behalf.

Mazhar Nazir, 49, was found Nov. 2, 2008, dead of a bullet wound to the back of the head, sitting in the driver's seat of his cab near a parking garage on Greensboro Drive. His last fare, Evan D. Gargiulo, 23, made phone calls with Nazir's cellphone and reported his own cellphone and wallet stolen to D.C. police but never reported shooting Nazir, Fairfax Chief Deputy Commonwealth's Attorney Ian M. Rodway said.

Gargiulo initially claimed that Nazir had tried to attack him because Gargiulo didn't have the $130 fare for a trip from a Washington nightclub to Gargiulo's Reston apartment, and then to Gargiulo's parked vehicle at the Rotunda apartment complex in Tysons Corner.

Renowned psychologist Stanton Samenow, who often testifies against defendants making an insanity claim, examined Gargiulo and found that he was "psychologically destabilized," defense attorney Steven Garver said, and "was unable to distinguish right from wrong as a result of that mental illness."

-- Tom Jackman