An Alexandria General District Court judge, learning that the suspect in the robbery-related murder of a government economist last week has an extensive criminal record, set the defendant's bond yesterday at $140,000.

"I find this man a clear and present danger," Judge Robert T.S. Colby said of Boggess Steve Davis, 20, charged with burglary and robbery in connection with the slaying of Steven Marston and the shooting of Marston's wife, Martha Riche, Jan. 2 at their Greenway Place town house in Parkfairfax.

Davis was arrested Monday night along with two juveniles also charged in the shootings. Davis' bond had been set at $20,000 by a magistrate.

Steve Rideout, Davis' court-appointed attorney, appealed to Colby yesterday to reduce the bond. Commonwealth's Attorney John E. Kloch argued that Davis should be held without bond because of a criminal record that includes convictions for trespassing, abduction with a firearm, carrying a concealed weapon and house breaking.

Davis is currently on parole from a five-year sentence for the abduction, which occurred in Fairfax County. He is also on probation for a conviction for breaking into a Prince George's County home. A preliminary hearing for Davis is scheduled for Feb. 2.

Kloch yesterday asked the city Juvenile and Domestic Relations Court to permit the juvenile suspects, one of whom is charged with Marston's slaying and the wounding of his wife, to be tried as adults. A decision on the request is expected in March, Kloch said