These are available at Amazon. For example, Columbo: The Helter Skelter Murders:
The wife of a wealthy Los Angeles businessman is found murdered in her bed with her lover, with the words Helter Skelter painted in blood on the walls. Columbo, America's favorite TV detective, must ask himself whether the horror of the Manson himself is ordering a fresh new round of atrocities from his San Quentin prison cell?And The Grassy Knoll:
To solve this case Columbo will have to face evil incarnate: the madman known simply as "Charlie."
After the murder of controversial talk-show host Paul Drury, Lieutenant Columbo must unravel the thirty-year-old mystery of the assassination of President Kennedy, a crime whose perpetrator Drury had been about to expose on his final show