At the trial it was established that at this location, one of the boys threw blue Humbrol modelling paint, which they had shoplifted earlier, into Bulger's left eye.[11] They kicked and stomped on him, and threw bricks and stones at him. Batteries were placed in Bulger's mouth.[22] Police believed some batteries may have been inserted into his anus, although none were found there.[3] Finally, a 22-pound (10.0 kg) iron bar, described in court as a railway fishplate, was dropped on him.[23][24][25] Bulger suffered ten skull fractures as a result of the iron bar striking his head. Dr. Alan Williams, the case's pathologist, stated that Bulger suffered so many injuries—42 in total—that none could be isolated as the fatal blow.[26]

Police suspected that there was a sexual element to the crime, since Bulger's shoes, socks, trousers and underpants had been removed. The pathologist's report read out in court stated that Bulger's foreskin had been forcibly retracted.[23][27] When questioned about this aspect of the attack by detectives and the child psychiatrist, Dr. Eileen Vizard, Thompson and Venables were reluctant to give details; they also vehemently denied inserting some of the batteries into Bulger's anus.[3][18][28] At his eventual parole, Venables's psychiatrist until he was aged 21, Dr. Susan Bailey, reported that "visiting and revisiting the issue with Jon as a child, and now as an adolescent, he gives no account of any sexual element to the offence."[3]

Before they left him, the boys laid Bulger across the railway tracks and weighted his head down with rubble, in the hope that a train would hit him and make his death appear to be an accident. After Bulger's killers left the scene, his body was cut in half by a train.[29] Bulger's severed body was discovered two days later, on 14 February.[7] A forensic pathologist testified that he had died before he was struck by the train.