The Doppelgänger Gambit

<b>From the back cover of the Del Rey first edition</b><p>The starship broker OD'd on a particularly nasty drug - and his files showed his personal responsibilities for a series of space disasters. Suicide? Policewoman Janna Brill was ready to buy that, but her oddball sidekick, Mama Maxwell, smelled murder on the dead man's partner - and Mama Maxwell, for all his bizarre antics, had a reputation for being right. <p>The trouble was, the suspect had to be in the clear. The giant computer that kept hour-by-hour track of every citizen provided him with an absolute alibi. To nail the man, Mama would have to prove the computer wrong - and knock out the keystone of law and order for an entire country! <p>

According to reviews, the 2015 edition was revised and updated. On a side note: the interstellar ramjet 'Invictus' also features in Liberty's World by Lee Killough, see the link.