"48 HOURS MYSTERY" MAKES A DIFFERENCE BY PLAYING A CRUCIAL ROLE IN A COLD CASE

"THE BOY NEXT DOOR"

SATURDAY, AUGUST 18 (10:00 PM, ET/PT)

The nearly 20-year-old murder of Tricia Pacaccio remained unsolved until a 48 HOURS MYSTERY report aired in 2011, and now her alleged killer is facing a trial for her death and for two other unrelated murders. In 1993, Pacaccio had just graduated from high school and was looking forward to her future when she was brutally stabbed and dumped on the side porch of her Glenview, Ill., home. As Maureen Maher reports in this updated broadcast, investigators suspected air conditioner repairman Michael Gargiulo was the killer, but they didn't have enough evidence. That is, until the first 48 HOURS MYSTERY about the case aired. Within hours, two new witnesses came forward and turned the case in unexpected directions. Without 48 HOURS MYSTERY, the Pacaccio family might never have gotten the answers to what happened to Tricia they sought for so long.

Follow 48 HOURS MYSTERY on Facebook and Twitter.