"In no way could we connect him to the disappearance," Vanore said, adding that being unable to close the case was especially frustrating for those involved with the investigation.
"There's a lot of us that worked that case [who] think about it a lot," he said, "It bothers us."
Thomas, 44, headbutted a Philadelphia police detective during an interview in that case in October 1999, a couple of weeks after Procopio went missing, and was charged with aggravated assault and resisting law enforcement.
Thomas was on probation in Montgomery County for fraud charges when he sped past the scene of a car accident in a stolen 2006 Infiniti SUV shortly before the fatal encounter with Fox.
Court records show that Thomas was involved in multiple court cases in Philadelphia in 1999 and 2000 for offenses including forgery, firearms violations, aggravated assault and welfare fraud.
Charges were also filed against him in Upper Merion Township for forgery and theft by deception on July 1, 2005, according to court records.
He pleaded guilty to the charges, which arose after he used $140 worth of counterfeit Acme market gift certificates, officials in the Montgomery County District Attorney's Office said. He failed to show up for his original arraignment in 2005 and was a fugitive for seven years until he was arrested on May 21. He pleaded guilty to the charges the next day, said D.A. Risa Vetri Ferman.
After speeding past the accident on East Ridge Pike near Chestnut Street about 5:40 p.m. Thursday, Thomas hit a car and fled the scene, officials said.
Fox and his canine partner, Nick, pursued him and found the car abandoned near the Schuylkill River trail, authorities said.
Thomas, hiding behind tall weeds on a hill on Conshohocken Road near Ernest Station Road just south of the Pennsylvania Turnpike, fired four shots at Fox, fatally wounding the officer in the head.
Soon after, Thomas committed suicide by shooting himself once in the chest, authorities said.
Contact Phillip Lucas at firstname.lastname@example.org or 215-854-5914. Follow him on Twitter @UnPhiltered. Read his blog at PhillyConfidential.com.