CONNECTICUT (WABC) -- One of the last phone calls William "Billy" Smolinski made before disappearing in Connecticut back in August 2004 was to a man who was also romantically involved with a woman Billy had been dating.
Billy left a voicemail telling the man to "watch his back."
Police believe Billy was murdered, but by whom? And where is his body?
Billy's heartbroken parents have been trying to find him for two decades.
Eyewitness News investigative reporter Kristin Thorne steps in to help.
ABOVE: Watch the extra segment, "William 'Billy' Smolinski - From the Case File"
Kristin also tracks down persons of interest in Billy's disappearance and pushes them for the truth.
ALSO VIEW | Earlier episodes of "Missing" with Kristin Thorne
Kristin finds that the puzzle pieces lie across Connecticut -- witnesses who saw strange things happen at the time of Billy's disappearance.
For instance, a young girl said she saw men in the woods carrying what she believed to be a body; a woman saw a white truck matching Billy's in the woods behind her house; and a group of 20-year-olds hanging out in a parking lot late at night saw a man walk into a deserted driving range carrying large bags.
There's a $60,000 reward for information leading to the whereabouts of William "Billy" Smolinski. If you know anything about his disappearance, call the Waterbury Police Department at 203-574-6941 or the Crime Stoppers anonymous tip line at 203-755-1234.
If you are missing a loved one, you should register them in the National Missing and Unidentified Persons System. You can also look up a missing loved one there.
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