Boston Police report charging Tyshawn Pereira of Mattapan, 21, with the July 11 murder of Jean Louis on Bailey Street. Two other men, Michael Johnson-McNeil, 19, and and Bobby Robinson-Gilmere, 21, both of Dorchester, were charged as accessories after the fact.

Police report Pereira was already in custody on an unrelated matter. Johnson-McNeil and Robinson-Gilmere were arrested Friday by detectives from the homicide, gang and drug-control units, police say.

The three are scheduled for arraignmentMonday in Dorchester Municipal Court.