Thornton Police said a driver involved in a crash that killed a motorcyclist Saturday night has come forward. The crash happened about 10:45 p.m. near East 104th Avenue and Fox Run Parkway, according to police. A 37-year-old man was riding a motorcycle west on East 104th Avenue when he lost control and crashed, police said. A witness told officers that a black SUV cut in front of the motorcyclist, contributing to the crash. The man was taken to the hospital where he later died from his injuries, according to police. Police said their investigation found the SUV and motorcycle made contact. They also believe the motorcyclist was speeding, and the SUV driver was not. Police said the driver of the SUV, an 18-year-old, has come forward. Investigators are continuing to gather information about the circumstances surrounding the crash.