South Boston teen arrested in beating death of homeless man

Police have arrested a 17-year-old South Boston youth in the beating death Aug. 26 of a homeless man.

Prosecutors alleged yesterday that Thomas Grealish beat Mario Acosta with a baseball bat and kicked him outside 56 F St. Acosta, 40, died Tuesday at Boston Medical Center.

He was the city's 47th homicide of the year and one of the victims in a spate of attacks on the homeless.

Grealish was arrested Wednesday in South Boston and charged yesterday in South Boston District Court with two counts of assault and battery with a dangerous weapon and one count of assault and battery. Bail was set at $125,000, and Grealish was ordered to return to court Oct. 3.

Suffolk District Attorney Daniel F. Conley said that based on the results of Acosta's autopsy, authorities will determine whether to charge Grealish with murder.

Conley said police believe Grealish did not act alone, and they are looking at other potential suspects in the assault, which unfolded shortly before 1 a.m.

Grealish's lawyer, Lisa Medeiros, declined to comment on the case when reached at her office yesterday.

Lyndia Downie, the president and executive director of the Pine Street Inn, a homeless shelter in the South End, said she is relieved that an arrest has been made, but concerned about the recent spate of violence against the homeless.

Kenny Kane, a 48-year-old homeless man, was found badly beaten in an alley between Newbury Street and Commonwealth Avenue in October. Another homeless man, Steven Neiber, was found dead outside St. Anthony's Shrine in downtown Boston last month. The cause of Neiber's death remains under investigation.

Downie said her outreach staff knew Acosta because they would bring him food and other provisions two or three nights a week. She said her staff had been unable to persuade Acosta to seek treatment for substance abuse.

''He was a nice guy, really struggling, unfortunately, with a substance abuse issue on the street," Downie said.

''He was someone who tried to stay pretty inconspicuous and anonymous, ironically. He stayed out of people's way."

Downie said she believes Acosta had family in the Boston area, but she does not know where.

Suzanne Smalley can be reached at ssmalley@globe.com.