Arthur Maling published fifteen novels over a near-twenty year period. Decoy was his debut; its protagonist/narrator is, according to the jacket flap blurb, a sciatica-suffering "home town boy" who agrees to deliver some papers for his half-brother to Mexico. On the plane he meets a girl with influential Mexican friends, and before too long the corpses start piling up and the US Treasury Department gets involved.
Used availability for Arthur Maling's Decoy