Most convicts have committed multiple felonies. They had eluded arrest and conviction on most of their offenses.
There were several cold case murders in the tiny town where I grew up that went unsolved for 30 years.
The guy was from 2 states away, only got caught when he came back 3 decades later to kill again. That’s when they finally got a confession out of him.
He’d gone undetected for 20 of those years because he was in prison in another state for unrelated crimes.