The wealthy real estate heir was charged in Westchester, New York, with second-degree murder in the decades-old disappearance.
The 23-year-old had been named a person of interest in the disappearance of his fiancée, whose body was found in a Wyoming national park in September.
Officials are reportedly examining Trump National Golf Club Westchester for possible tax fraud.
Cruz killed 14 students and three staff members on Valentine’s Day 2018 during a seven-minute rampage through a three-story building at Stoneman Douglas.
Prosecutors planned to seek the death penalty against William George Davis for the lethal injections in 2017 and 2018.
Cruz’s trial is likely to skip to the penalty phase, with a jury deciding his sentence for the 2018 mass shooting in Florida.
John T. Earnest avoided the death penalty with his plea in San Diego Superior Court.
Michael Leon Brock was filmed appearing to hit and push officers with the metal rod while wearing a hoodie reading "God, Guns and Trump."
Daniel Hale said guilt over participating in lethal drone strikes in Afghanistan led him to leak government secrets about the program to a reporter.
The sailor was a member of the USS Bonhomme Richard, but no name was released, no other details were provided, and the motive remains unclear.