Who is Terry Lennox from The Long Goodbye and what is their importance?

Terry Lennos, also known as Paul Marston and Cisco Maioranos, first meets Marlowe outside the club when Lennox is so drunk that he can't sit in the car seat. When they next meet, Lennox is drunk on a street, and Marlowe saves him from being arrested.

Terry married Eileen Wade as a young man, but she thinks he died in the war. In actuality, he saved the lives of two comrades, and they helped him when it appeared he'd be accused in the murder of his current wife, the wealthy Sylvia Lennox. Terry calls on Marlowe to help him reach an airport in Tijuana when he is apparently running from the law after killing Sylvia. Marlowe never believed Terry did it, and he continues to try to clear Terry's name though his friends have already arranged to fake his suicide and actually want Marlowe to leave the case alone.