By Shannon Stapleton BALTIMORE (Reuters) - Mourners will gather at a North Baltimore funeral home on Sunday to remember a 25-year-old black man who died a week ago while in police custody, an unexplained death that brought thousands to the city's downtown on Saturday to protest police violence. The wake for Freddie Gray on Sunday afternoon comes the day after the largest demonstration yet since he died on April 19 and two weeks after a foot chase with patrol officers, his eventual arrest and a ride in a police transport van. Anthony Batts, the city's police commissioner, said on Friday that officers who detained Gray failed to give him timely medical attention for a spinal injury he suffered in custody. The head of the Baltimore police union said this assertion was premature and apparently "politically driven." Gray joined a long list of black men who have died under questionable circumstances during police encounters in recent months.