Already serving a lengthy sentence for a series of Baltimore County robberies, Anthony Bruce faces up to 30 more years for attempted second-degree murder.
A Washington County Circuit jury found Bruce guilty of that offense Tuesday after two hours of deliberations.
Bruce was charged with stabbing his cellmate at the Roxbury Correctional Institution a dozen times last June.
Bruce, 35, was found not guilty of attempted first-degree murder.
Defense attorney Eric Reed pushed for sentencing following the jury's verdict but Circuit Judge Donald Beachley postponed sentencing, saying he wanted to know more about Bruce's past.
"He's a three-time loser," said Assistant Washington County State's Attorney Joe Michael.
Indicted by a grand jury last summer, Bruce was accused in the June 27, 1998, stabbing of the RCI inmate who was attacked after returning from a shower in the segregation wing.