Almost 13 weeks ago, Phylicia Simone Barnes vanished from her half sister’s North Baltimore apartment. She was 17, an honor student and a track star visiting from Monroe, N.C.

No one saw anything unusual. No video camera captured an image of her anywhere in the vicinity. No physical evidence has been found.

“Her trail ends at the front door of the apartment building,” said Baltimore Police Department spokesman Anthony Guglielmi. “At this point, we have no idea what happened.”

Her case is the focus of an investigation that stretches from Baltimore to her rural home town, 25 miles southeast of Charlotte. It has attracted national media attention and been featured on “America’s Most Wanted” because Phylicia, a high-achieving teen, does not fit the typical profile of a runaway. Police immediately suspected foul play.

She was not involved in unlawful activity. She had no history of mental illness. The last person to see Phylicia — her half sister’s ex-boyfriend — said he saw her asleep on the couch when he left the apartment early in the afternoon of Dec. 28.

Detectives from Baltimore and FBI agents traveled to Monroe last month. Her school locker and trees around the community are decorated with ribbons in purple, Phylicia's favorite color, and classmates have raised $25,000 of a $35,000 reward in the case.

Baltimore police are urging the media to aggressively cover the investigation, hoping to draw out witnesses. Her image has been posted on electronic billboards across the country, and her pretty face smiles back from thousands of milk cartons, newspaper inserts and mailed circulars. Dozens of newspapers, CNN and local TV news programs have told her story.

“The goal is to reach into millions of homes to touch as many people as we can in the hopes that we find that person who knows something,” said Ernie Allen, president and chief executive of the Alexandria-based National Center for Missing and Exploited Children.

Former D.C. police chief Isaac Fulwood Jr. said the disappearance of African American teenagers often does not attract much media attention.

“For whatever reason, we don’t place the same value on young African Americans, female or male,” said Fulwood, chairman of the U.S. Commission on Parole. “We always assume that there is something that they did behind them disappearing, so therefore the news media, even the police, don't pay the same level of attention.”

But in Phylicia’s case, Baltimore police responded with extra resources within days of her disappearance.

“I’ve got a core group that has been taken out of rotation to work only on [finding] Phylicia,” said Maj. Terrence McLarney, commander of the Baltimore police homicide division. “They have handled upwards of [200] leads that have taken us nowhere. I would be less than candid if I did not say that we're frustrated.”

Phylicia is 5-foot-8 and weighs 120 pounds. She has long, straight black hair and chocolate skin. She has a tattoo of a red rose on her right ankle.

She was last heard from about noon Dec. 28 when she texted her half sister, Deena Barnes, 28, with whom she had stayed in the 6500 block of Eberle Drive, near Reisterstown Plaza, since arriving in Baltimore on Dec. 17 for a holiday visit.

Phylicia initially was listed as a runaway but was reclassified as a missing person after she failed to show up for her Jan. 2 flight home to North Carolina. She was set to graduate from private Union Academy High School this year and attend Towson University and has never been in trouble, McLarney said.

“We have people who leave who have emotional or mental issues or substance-abuse backgrounds,” McLarney said. “You talk to the family and you find out they have disappeared before. . . . We have none of that with Phylicia.”

Phylicia went to work most days with Barnes, a pharmacy technician, or another half sister, Kelly Barnes, 25, assistant manager of a day care in Columbia, relatives said. She also has a half brother, Bryan Barnes, 23, in Baltimore. She kept in touch with friends and family by calling, texting and posting on Facebook, police said.

The trip to Baltimore was among several Phylicia had made since connecting with her half siblings on Facebook a few years ago. Their father, Russell Barnes, and her mother divorced when she was young and Phylicia did not have contact with her father until she reached out on the Internet.

Deena Barnes said she and Phylicia grew close immediately. “It was like I had a twin,” she said.

One of their first outings was shopping for a Christmas tree.

“I have allergies, so we couldn’t get a real one,” Barnes said. “We had to look a lot because most of the artificial trees were sold out. We finally found a white one, and we bought red lights and decorations for it. We decorated it together and made hot chocolate and listened to Christmas music.”

In a telephone interview from Monroe, Phylicia’s mother, Janice Sallis, said she thought something was wrong when she was unable to reach her daughter. whom she calls by her middle name, Simone. “When I hadn’t been able to reach her by 8 p.m., I called Deena. She said, ‘I was just about to call you. We can't find her. She’s missing.’ ”

Deena Barnes said that the night before Phylicia disappeared, Dec. 27, they had returned home from her job in the early evening.

Her ex-boyfriend and former roommate, his 16-year-old brother and his 21-year-old cousin, who is also a roommate, were at the apartment, she said.

When Deena Barnes left for work the next morning at 8:45, Phylicia was asleep in a bedroom they were sharing. The ex-boyfriend went to the apartment that morning to pick up his brother. Phylicia texted her later that he was there and doing laundry. Barnes exchanged texts with Phylicia and her ex-boyfriend and had at least one phone call with Phylicia. But just after noon, Phylicia stopped responding. to texts and calls went to voice mail. At 1:04 p.m., the ex-boyfriend texted her that Phylicia was sleeping and had told him she later planned “to go get something to eat.”

Phylicia often went to the food court at Reisterstown Plaza across the street,

Barnes said, but police found no evidence that she had been there. Barnes said she returned home from work at 6 p.m. and, after making a round of calls to find Phylicia, contacted police at 7:30 p.m.

Since then, detectives have interviewed dozens of people, followed up on tips from as far away as Washington state and conducted several searches, but no suspects have been identified, McLarney said. McLarney was interviewed in February. On March 7, he was placed on administrative leave with pay pending the outcome of an investigation into a traffic accident involving his police cruiser.

Deena and Russell Barnes, with loved ones and volunteers from the Guardian Angels and the Nation of Islam, have made several searches. Police said another search will be conducted within two weeks.

Deena wears a shirt adorned with her sister's picture and the words: “Have you seen her? Please call police at 1-866-756-2587.”