Atlanta , Georgia ( CNN ) -- Bobby Maurice Tillman , the Georgia teen stomped to death outside a home where a party was being held , died from a lacerated heart , Douglas County Coroner Randy Daniel told CNN Tuesday . He said the 18-year-old likely suffered a break in a rib bone , which in turn punctured his heart . If the young man had not been stomped , he probably would not have been injured in that way and would have survived the beating , Daniel added . Police say Horace Damon Coleman , 19 , Emanuel Benjamin Boykins , 18 , Quantez Devonta Mallory , 18 , and Tracen Franklin , 19 , stomped and beat Tillman outside a party in metro Atlanta over the weekend . The four men are facing felony murder charges . Douglas County Sheriff Phil Miller has said the attack happened after some girls got into a fight , and one of them hit a boy . That boy , according to Miller , said he was n't going to `` hit a girl , '' but the next guy who came by was going to get `` beat down . '' Tillman walked by . Miller said the victim was a `` little guy , 18 years old , 5-foot-6 , weighed 125 pounds . '' `` He was small in stature , but ... his spirit and his strength were bigger to me than this world , '' Tillman 's mother , Monique Rivarde , told CNN Tuesday . `` My son was bullied by four cowards . '' No drugs or alcohol were found at the scene , according to the sheriff , who said he does n't expect any more charges in the case . CNN 's Tristan Smith contributed to this report .
Bobby Maurice Tillman , 18 , was beaten to death outside a party . A broken rib most likely punctured his lung , the report says . Four teens face attempted murder charges .