WATERBURY, Conn. -- Four years after a Waterbury man went missing, investigators have conducted a forensics analysis on the man’s truck.

Based on new developments, police said they have decided to look at the truck for possible clues, including DNA evidence, that could lead them to Billy Smolinksi.

Police To Search Truck In 4-Year-Old Case

Smolinski’s parents said they’ve kept the truck in storage because they believed it might hold some answers. His mother, Janice, said they "felt the truck may have been involved in the crime, but the police ignored our concerns at that time."

"It took four years to reach the point we are at right now, with constant work to keep Billy's name out of the cold case files," she said.

Connecticut State Police Lt. Paul Vance said Tuesday that he had no comment because it’s an open case.

The 31-year-old construction worker disappeared Aug. 24, 2004.

Over the summer, police excavated a Seymour Farm in connection to the case but found nothing.

The Smolinskis are currently in Denver, Colo., where Janice recently acted as the keynote speaker for an event held by Families of Homicide Victims and Missing Persons Inc.