with their own T-shirts and a tire iron while letting them fade in and out of consciousness, although some victims were stabbed or battered to death. One victim, Darin Kendrick, was forced to drink hydrochloric acid; three victims had ice-picks driven into their ears and another victim, Mark Shelton, died of shock from impaling. According to one attorney present throughout Bonin's subsequent confessions, the escalating levels of brutality he had exhibited toward his victims had been similar to that of a drug addict requiring an ever-greater increase of dosage to attain a satisfactory level of euphoria. Bonin himself later likened his homicidal urges to that of an addiction, emphasizing to neurologists his scarcely being able to wait for the onset of dusk to begin his cruising and referencing his feelings of extreme restlessness and sexual frustration in the hours prior to his murders, emphasizing that he had felt an intense sense of excitement as he drove in search of his victims. Reserving Sundays for his girlfriend, he typically cruised the freeways on Fridays and Saturdays. Bonin also later described his feeling pleasure at hearing his victims scream, as well as sodomizing his victims – particularly in an upright position – without lubricant, causing them to rectally bleed and tear. In order to minimize the chances of a potential victim escaping from his vehicle, Bonin removed all inner handles from the passenger-side and rear doors of his van. He also stowed ligatures, knives, pliers, wire coat hangers, and other such instruments in his vehicle to facilitate the restraining and torture of his victims. The victims were usually killed inside his van before their bodies were discarded alongside or close to various freeways in southern California. In an apparent effort to avoid investigators connecting his crimes, Bonin often drove to various counties to discard his victims' bodies far from the site of their abduction. Dr. Albert Rosenstein, a forensic psychologist, predicted their killer was an intelligent sex offender in his late twenties or early thirties, had spent time in a psychiatric facility, was abused as a child, and that while bisexual, the killer "has [never] become comfortable with the homosexual side of his personality" and is repulsed by his actions, as is evidenced by the gruesome mutilation of his victims. In a minimum of twelve of the murders, Bonin – who considered murder a "group sport" – was assisted by one or