. >> reporter: we went to jersey city and found mario costa, a friend and mentor who first met arturofighter was 17. >> his dream was to become champion. >> reporter: as the years went by, costa says, arturo struggled with debilitating injuries. >> his eyes, the phone rang, he put his phone like this, an inch away from the eye. he got addicted to pain killers: percoset, vicodin, oxy, coke. he was just not himself. the losses were like somebody stabbing him in the back and the knife going through his heart. >> reporter: after a particularly devastating loss in 2005, gatti was hospitalized for an overdose. medical records show the doctors suggested a psychiatric consult. in child support documents, the mother arturo's daughter called it a suicide attempt. >> i told him, i said, "you have to talk to a professional. you have to go to a psychiatrist." >> reporter: another time, costa remembers an inconsolable arturo showing up at his new jersey bar and demanding to borrow his gun. >> he took his finger, like this. he said, "this is what i'm going to do," he shoved it in his mouth. and i fe

. >> reporter: we went to jersey city and found mario costa, a friend and mentor who first met arturoe fighter was 17. >> his dream was to become champion. >> reporter: as the years went by, costa says, arturo struggled with debilitating injuries. >> his eyes, the phone rang, he put his phone like this, an inch away from the eye. he got addicted to pain killers: percoset, vicodin, oxy, coke. he was just not himself. the losses were like somebody stabbing him in the back and the knife going through his heart. >> reporter: after a particularly devastating loss in 2005, gatti was hospitalized for an overdose. medical records show the doctors suggested a psychiatric consult. in child support documents, the mother arturo's daughter called it a suicide attempt. >> i told him, i said, "you have to talk to a professional. you have to go to a psychiatrist." >> reporter: another time, costa remembers an inconsolable arturo showing up at his new jersey bar and demanding to borrow his gun. >> he took his finger, like this. he said, "this is what i'm going to do," he shoved it in his mouth. and i