LILLIAN O'DONNELL has written some good police procedurals featuring Norah Mulcahaney, a New York City police detective. In Aftershock (Putnam, $7.95), she introduces a new heroine, Mici Anhalt, a caseworker for the Crime Victims Compensation Board. Unfortunately, Mici isn't made of the same stern stuff as Norah. There is a touch of cloying soft-headed sentimentality as Mici handles compensation claims and gets involved in the murder of a blackmailing society hairdresser who offers more than new coiffures to his clients.

Another good case of police detective work from Rex burns is The Farnsworth Score (Harper & Row, $7.95). Last year Gabriel Wager, a Denver cop who is a Chicano despite the name, made his first appearance in The Alvarez Journal to bring Burns the Mystery writers of America award for the best first mystery of the year. It's the drup scene again for Wager, an honest and intelligent cop who tells us what it does to a policeman's personal life when he goes under cover on a narcotics assignment. Burns has a brisk, naturalistic style to match the action. But addicts and dealers who vovabulary is limited to a few choice four-letter words do wear a bit thinafter long exposure.