BALTIMORE, May 5 (Reuters) - New U.S. Attorney General Loretta Lynch on Tuesday met with Baltimore officials and the family of a 25-year-old black man killed by police last month and vowed to help the city pursue police reform. The meeting in Baltimore came the week after the city's top prosecutor brought criminal charges against the six officers involved in the April 12 arrest of Freddie Gray, who suffered a spinal injury that led to his death a week later.