Indiana police are interviewing "persons of interest" in the disappearance of a college student last seen by a friend walking toward her apartment last Friday.
The Bloomington Police Department said Tuesday that anyone seen with Indiana University student Lauren Spierer in the hours before her disappearance is considered a "person of interest," though no suspects have been identified.
Spierer, 20, was reported missing last Friday afternoon. Lt. Bill Parker said Tuesday that she was last seen by a male friend walking home to her apartment in downtown Bloomington at around 4:30 a.m. Friday. He said foul play is suspected.
Parker said Spierer, who was seen walking alone and barefoot, spent the night partying with friends at a local bar before visiting a friend's apartment a few blocks from her own.
Parker said Spierer's shoes and cellphone were later found at the bar. Her purse and some keys were found along the route to her friend's apartment.
"We’ve had a lot of cooperation with the persons of interest," Parker said, adding that police have also searched the apartments of the friends last seen with Spierer.
Parker said video surveillance shows Spierer partying with friends Thursday night at Kilroy's Sports Bar. He said at approximately 2:30 a.m., Spierer and a friend walked to her apartment building, where they stayed for a "little while" before walking north to another friend's apartment. He said Spierer was last seen by a male friend leaving that building to walk home at around 4:30 a.m.
"That young man saw her walk in that direction," Parker told reporters.
Spierer, a 2009 graduate of Edgemont High School in Scarsdale, N.Y., had just completed her sophomore year at the university.
"She's an amazing girl," Monique Douglas, a friend and coworker of Spierer's mother, said in an interview with FoxNews.com.
Douglas described Spierer as a driven young woman with "great charisma" who was studying fashion merchandising.
The woman's parents, Robbie and Charlene Spierer, and her 25-year-old sister flew from their home in Westchester County, N.Y., to Bloomington over the weekend to join the search.
Robbier Spierer issued a public plea Tuesday for the safe return of his daughter.
"We need to know when you saw her, where you saw her," Spierer said at a press conference. "Every little piece of information is important."
The woman's family and police also said Spierer has a life-threatening heart condition, called Long QT Syndrome, that requires her to take medication daily.
Hundreds of volunteers continued their search for Spierer on Tuesday, scouring downtown Bloomington as well as wooded areas, construction sites and land around lakes.
The Hillel Jewish Center in Bloomington, where Spierer was active, said they have been working with police to assist in the search.
"The police are delegating which areas we’re going to search," Lance DaSilva, who works at the center, told FoxNews.com. "Yesterday we probably had around 400 volunteers. We’re getting a lot of people that want to help."
Spierer is described as 4 feet, 11 inches tall and weighing 90 to 95 pounds.
Police said Spierer has blue eyes and shoulder-length blond hair, though stressed her appearance may have been altered if she was abducted.
Anyone with information on her whereabouts it being urged to call the Bloomington Police Department at 812-339-4477.
Cristina Corbin is a Fox News reporter based in New York. Follow her on Twitter @CristinaCorbin.