If the victim weren't Cambodian, it might as well be 1940 for Alex Rasmussen, the Lowell (Mass.) private eye hired by Bhuntan Tran's socialite social worker, Ada Stewart, to find out who shot him to death. Since Rasmussen's wary ex-colleagues on the force are ready to write off the killing as another drug murder, it's up to him to dope out the link between hardworking Tran's death and those of half a dozen other Cambodian immigrants around the country, all the while maintaining his position in the Philip Marlowe Redux Society. Rasmussen's credentials are comically impressive: He has a wonderfully overripe line of patter (``Have you got a minute?'' ``Loads of them, one right after another''), keeps a .38 and a bottle of bourbon in his filing cabinet, traces Tran's murder to a Chandleresque cache of jade, watches his estranged wife dance away into the arms of a smooth dry-cleaning mogul (one shady past, two threatening sidekicks) who becomes the next victim, and enjoys the privilege of having everybody but his ex--from the client to a frowsy good-time girl to the comely jade expert at Haskell and MacKay--make a play for him in a vain attempt to distract him from the screamingly obvious solution. The latest winner of St. Martin's Best First Private Eye Novel Contest, and an unabashed wallow in the bad old days. As for the patter (``My control was unraveling like cheap socks''), forget Chandler; think S.J. Perelman.