A Stab in the Dark by Lawrence Block

Read again 2018. Very enjoyable, would like to read more in the Scudder series. 1981. PW: Nine long years have passed since the killer last struck - nine years since eight helpless young women were brutally slaughtered by an icepick-wielding maniac. The trail grew cold and the book was unofficially closed on a serial killer who stopped killing. But now "The Icepick Prowler" has confessed - but only to seven of the killings. Not only does he deny the eighth, he has an airtight alibi. Barbara Ettinger's family had almost come to accept that the young woman was the victim of a random killing. Now they must grapple with the shocking revelation that not only was her death disguised to look like the serial killer's work, but her murderer may have been someone she knew and trusted. Matthew Scudder has been hired to finally bring her slayer to justice, setting the relentless detective on the trail of a death almost a decade old, searching for a vicious murderer who's either long gone, long dead... or patiently waiting to kill again.