Amanda De Guio, who would now be 28 years old, was last seen on June 3, 2014. She walked out of her mother's home in Drexel Hill and left all of her belongings and her two small children behind.
Police say she became addicted to painkillers after a medical procedure, and later turned to heroin. Police now believe she was the victim of foul play.
Upper Darby Police Superintendent Michael Chitwood said the department has essentially reopened the case, saying this no longer appears to be a missing person case. He said investigators now believe they have to find a body.
"I've assigned two detectives to work around the clock to do what they initially did, the missing person investigation, now they're going to do a foul play investigation," said Chitwood.
Her mother, Joanne, is begging for anyone with information about her daughter's disappearance to come forward.
"There is somebody out there that knows something, and to not come forward in four years, how do you have a heart?" she said. "She has two children that need to know where their mom is, whether she's alive or not."
Amanda has a number of tattoos, including lips on her right buttocks, an Italian boot and "Tommy" on right torso area, "MF" inside lower lip, and "SC" on the left ring finger.
"It's time now. Somebody knows something, and we're hoping that one person will answer our prayers," Joanne De Guio said.
Investigators believe there are people who know more than they're letting on.
"One, two three people know what happened. They know what happened and so they're not telling the truth. They're not being honest, being frank," said Chitwood.
She is described as 5'2" tall and weighing 120 pounds with brown hair and blue eyes. She has a diagonal surgical scar on her upper and lower abdomen. She is known to frequently wear wigs and large jewelry.
According to police, De Guio was possibly involved in prostitution and posted on sites such as Backpage.com using the names of "Gianna," "Arianna," or "Crystal."
There is a $5,000 reward for any information that would lead to finding De Guio, and to the arrest and conviction of those responsible.
Anyone with information Pennsylvania Crime Stoppers Toll Free at 1-800-4PA-TIPS.
Send a News Tip to Action News
Learn More About 6abc Apps