Matthew was a close friend, ally, and chief aide of John Kirin, the current alias of the Immortal, Kage, who was living as a spiritual teacher in Seacouver.
Matthew assisted Kirin in the running of his mission, and in providing meditations to their followers. It is unknown how long Matthew had aided Kirin, but it seems their association had been over many years.
As a child, Matthew was abused physically, mentally, and verbally by his father, who often beat him while drunk. After years of abuse, he murdered his father and served five years in prison. He sought out John Kirin as a spiritual guide and guru, and to aid him in dealing with his history of abuse. Matthew was highly protective of Kirin, to the point where he harassed and threatened anybody he saw as a threat to Kirin's mission. To Matthew, Kirin became a rock and a source of spiritual and emotional support. Years of abuse had given Matthew a very negative view of humanity, which Kirin took upon himself to correct and uplift. His past also gave him a strong intuition, especially as to the negative and harmful motives of others. He correctly sensed, at Duncan and Kage's initial meeting, that Duncan wanted to kill Kirin out of revenge for his past wrongs.
In Seacover in 1995, Kirin/Kage was aiding homeless people, when he "died" when saving Matthew from an oncoming vehicle. Due to his reverence of Kirin, Matthew was not at all surprised when Kirin resurrected despite having been declared dead by Dr. Anne Lindsey.
This alerted Duncan MacLeod, as he suspected that an Immortal was involved. MacLeod's suspicions were proven correct, as he uncovered that Kirin was Kage, an enemy of his from the Spanish Civil War and the Khmer Rouge regime in Cambodia.
In his effort to protect Kage, Matthew warned off an investigative reporter, Todd Milchan, who had his own suspicions on Kirin's intent and purpose as a preacher.
When MacLeod confronted Kirin/Kage on his purpose as a preacher, Matthew again was protective of his friend, unaware as to the origin of MacLeod's hostility. The reporter, who had followed Duncan to his home/dojo, suspected that Duncan and Kirin/Kage had some past enmity, and wished to investigate this further. Matthew, however, had followed him, and killed the reporter, shooting him dead in MacLeod's dojo, for not heeding his initial warnings.
Duncan, believing Kirin to be as evil as he had been in the past, thought he killed the reporter as both a warning and as a way of goading of him. MacLeod sought him out for an intended final confrontation. Kage described his moment of epiphany and the beginning of his need for redemption. When he refused to fight, MacLeod could not just kill him, and he began to believe that Kirin had perhaps really turned away from his centuries of evil deeds. Both were unaware that Matthew was listening to them and watching their confrontation.
Later, Matthew broke into Duncan's apartment, and threatened him with a .38. He demanded Duncan to tell him about Kage, who he was, what had they meant about the past murders. Kirin arrived, suspecting Matthew would show up, and tried to talk him out of firing his gun, telling him that he had also called the police to inform them of Matthew's murder of the reporter.
Matthew accused him of being a liar, a conman, and a phony. Feeling overwhelmed, disillusioned, and angry, he shot Kirin, believing him to be dead. He started to run, but with the arrival of the police, he was trapped. Duncan tried to persuade him to turn himself in, but Matthew, said, "Nobody can help me now. I loved him, and I killed him....There's nothing left." He ran outside, smiled at MacLeod and deliberately pointed his weapon at the heavily armed police - effectively committing suicide.
Kirin showed remorse, blaming himself for Matthew's death, and for the deaths Matthew caused.