Ron Martinez! Wow, there’s a name I remember. I loved his Interplanetary Spy books. Well, the whole series. But The Star Crystal (#6) was particularly cool to me. It’s bout the theft of priceless art on a mobius-strip spaceship.
It also had the clever trick of [spoiler]the final page leading to a “death” ending instead of the usual “you win.”
#4, Space Olympics, was also very good.
His comment “I was good at it” is indeed correct … these are IMHO two of the strongest in the series, though I liked them all.
Also I have been mispronounicing Preiss for years!