By Joe Holden

PHILADELPHIA (CBS) — Toni Lee Sharpless was a nurse from Chester County who was last seen leaving a party in Lower Merion and disappeared without a trace. Her case has baffled investigators ever since.

Sharpless’s case file hasn’t seen activity in several years. The missing nurse from West Brandywine Township, Chester County, was last seen leaving a party in Lower Merion Township the night of Aug. 22, 2009. She had set out earlier that evening for a night of fun in Center City Philadelphia.

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“I vowed to help the family, if they wanted it,” Eileen Law said.

Law, a private investigator, has pored over the case for more than a decade.

“It’s a cold case to the rest of the world, it’s not a cold case to me,” Law said.

Family has long hoped Sharpless would come home to her daughter she left so many years ago.

“When her daughter ran to me saying, ‘please find my mommy,’ crying, that moment, that face changed everything for me,” Law said.

Law has worked the case pro-bono. Her office is filled with reminders of Sharpless.

A month after her disappearance, a license plate reader got a hit in Camden. The plates were registered to Sharpless’s car.

The pushpins on this map track where Law received tips about possible sightings.

And then in 2012, came the letter.

“The writer says that he was paid $5,000 to move a car out of Brooklawn, New Jersey,” Law said.

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It’s claimed the car ended up in Boston, but that remains a loose end.

Working the case too, the investigator who’s been assigned to it from the very beginning, West Brandywine Cpl. Russell Moore.

“Now I believe she is deceased,” Moore said, “and I would love to give the family some closure.”

Sharpless’s family declined to speak to CBS3 Mysteries.

Some years ago, accepting reality, police say they had her declared legally dead. Now, the mission of the investigation is to locate Sharpless’s remains and bring her home.

Police have ran down, checked off and disproven most of the theories developed early on — even one suggesting Sharpless may have had too much to drink and ended up losing control of her car.

“They also dredged the Schuylkill River for vehicles, that turned up nothing,” Moore said.

For Law, the case carries personal weight.

“Some just get to you. They get under your skin and into your heart and very soul,” Law said, “and that’s what happened with this.”

Who knows what happened Toni Sharpless?

“I would love to be able to get closure for the family, for her daughter, for her mom, her sister,” Moore said.

“Until my dying day, my last breath, I will look for Toni,” Law said.

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If you have any information that could help detectives find Sharpless, please call the West Brandywine Police Department at 610-380-8201.