This episode is brilliantly written and acted.
The first half consists of a series of comic vignettes as the detectives seek to build a case against billionaire businessman Richard Peterson for the murder of his friend and coin dealer. There are several minor characters, each with only a minute or two of screen time. They include the "Italian aristocrat" who serves as the two men's mistress, but is actually from South Carolina; the rich businessman who "gets horny" thinking about coins as he works on his luxury yacht; the haughty restaurateur who refuses to divulge his clients' secret conversations; and the nubile young reporter who tried and failed to invite Peterson back for "coffee". All have memorable interactions with Briscoe and Curtis, Briscoe having a wonderful time flirting with the ladies.
Things turn serious when the focus of the investigation shifts to Judith Sandler, the child of a Holocaust survivor. Her father owned the missing coins, but was unable to recover them from a Swiss bank after the war. Sandler, wonderfully acted by Karen Allen, has an extreme personality: touchy, overwrought, claustrophobic. It soon becomes apparent that she is the real killer, but the evidence against her is suppressed when Ross exploits her claustrophobia in order to get her consent to search her apartment.
While Sandler represents tragedy, Peterson (skilfully acted by Michael Willis) represents comedy: a larger-than-life character who's having so much fun collecting coins and running his business empire that it's hard to dislike him, even when his lies unwittingly set into motion the tragic murder of his friend.
McCoy gets less screen time than usual, but Ross shines. Note especially her first appearance: the camera almost caresses her as she glides into the frame during Peterson's interrogation.
Law and Order had its strong and weak spells over its twenty years, but this episode sums up what could happen when everything came together -- perfect writing, camera-work and acting.