Muscoy is the owner of the pickup truck believed to be involved in the accident that killed 17-year-old April Maher on Oct. 7.
An anonymous tip led authorities to the truck in San Bernardino, but Lemus has not come forward to police.
Anyone with any information is asked to call the Highland Police Department.
- Get more local news headlines from the Inland Empire
- Have a news tip? Send your tips, video, or pictures