The murder charges against a Suburban Hospital employee who police say killed his boss over workplace disputes have raised questions about how a man with a violent past slipped through the background checks the hospital says it routinely employs. Suburban spokeswoman Ronna Borenstein-Levy said the hospital conducted a background check on 49-year-old engineer Keith D. Little — accused of stabbing his supervisor, Roosevelt Brockington Jr., more than 70 times in Suburban’s boiler room — but that check “did not return information on prior arrests and convictions.”

But court records show Little was charged with second-degree murder in a 2003 D.C. slaying but was found not guilty in a jury trial. He also served about six years in prison after he was convicted of several assault charges and obstruction of justice related to a 1984 attack.