04/27/2012 02:08 pm ET Updated Apr 28, 2012

Vernon Davis' Brother Arrested For D.C. Hammer Attack, May Be Connected To Tourist Murder

WASHINGTON -- The younger brother of San Francisco 49ers tight end Vernon Davis was arrested Thursday night, found with what WTOP-FM is describing as a "bloody claw hammer" that police say was likely used to attack a woman in D.C.'s Petworth neighborhood on Thursday night.

WJLA-TV/ABC7 reports that Michael Davis was arrested on Thursday night after a 19-year-old woman was hit in the head not far from where murdered Denver tourist Gary Dederichs was discovered on Tuesday, just off Emerson Street NW.

Davis was found soon after the attack with the hammer, which may also have been used in other recent attacks, including Dederichs.

Davis has been charged with aggravated assault. Police believe Davis may also be responsible for Dederichs' murder, and two other recent attacks that sent their victims to the hospital with severe head trauma.

D.C. Mayor Vincent Gray says that the 19-year-old Davis "appears to be mentally ill," reports WTOP. The mayor says he does not want to conclude that there is a pattern to the attacks, according to the radio station. But there's "[t]he same m.o. as the other three incidents," Gray said. "He was arrested, and we think obviously we have a suspect."

WAMU-FM reports that Metropolitan Police Department Chief Cathy Lanier asked people in walk in pairs or groups in D.C.'s Petworth neighborhood, where all the attacks have taken place:

"All three of the victims did suffer pretty significant blunt force trauma to the head and, preliminarily, it seems the victims were assaulted suddenly and without provocation," says Lanier. "Since it appears that all the individuals were alone at the time, we're asking that residents in the area walk in pairs or in groups when at all possible until we get more information."

Vernon Davis, who graduated from D.C.'s Dunbar Senior High School and played college football for the University of Maryland, sent out a foreboding tweet on Thursday night:

CORRECTION: An earlier version of this post incorrectly named the call letters for WJLA-TV.