The Suffolk County District Attorney’s Office has completed its inquiry into the death of a prisoner at the Suffolk County House of Corrections, finding that the inmate died of a pre-existing heart condition and not criminal activity.

Darryl Leslie, 41, of Dorchester died of a cardiac dysrhythmia on the night of Dec. 31, 2007, after being transported from his cell to a segregation unit. Leslie was transported after a nurse at the House of Corrections found a note in the unit’s sick call box indicating that Leslie might harm an employee.

Forensic pathologists at the Office of the Chief Medical Examiner attributed Leslie’s fatal dysrhythmia to mitral valve prolapse, an abnormality of the heart valve from which Leslie suffered. This condition led to the dysrhythmia from which Leslie suffered and ultimately died. This condition was not known to Sheriff’s personnel and was not listed on his medical records.

Leslie was handcuffed and removed from his cell by two members of the Sheriff’s Emergency Response Team. The group was met by two additional SERT members at 9:13 p.m. as they arrived at the building housing the segregation unit. Leslie was at this time becoming more resistant to the move, eventually trying to kick and bite the officers. Additional SERT members met the group as they approached the segregation unit and, together, applied Emergency Response Belts – used to carry violent or injured persons – to his upper and lower torso.

At about 9:22, four corrections officers carried Leslie into the segregation unit using handles attached to the Emergency Response Belts. As they did so, they could feel and hear the Velcro on one of the straps coming unattached. The belt was tightened and Leslie was carried into the segregation cell.

On entering the cell, the officers put Leslie on the floor and observed that he was not moving and not responsive. A lieutenant at the scene requested medical assistance at this time, and a follow-up call to determine if that assistance was en route was made at approximately 9:24. An on-call nurse responded to the cell, checked Leslie for a pulse, and found none. Officers then commenced cardiopulmonary resuscitation on Leslie until members of the Boston Fire Department and Boston EMS arrived. Leslie was transported to Boston Medical Center, where he was pronounced dead.

At no time did any correction officer punch or kick Leslie. No baton, chemical spray, or other implement was used to subdue him. A complete autopsy found no bone fractures, internal damage, bruising, bleeding, or indication of blunt force trauma.

Suffolk prosecutors and Boston Police homicide detectives today met with members of the Sheriff’s Department and members of Leslie’s family to inform them of the investigation’s findings. Prosecutors recommended that the Sheriff’s Department adopt policy changes that would allow or mandate more rapid medical assessments of restrained inmates to reduce the likelihood of a similar incident.