The body found in a Maryland river is that of missing Monroe teenager Phylicia Barnes, police said Thursday.

Barnes, a student at Union Academy, went missing in late December while visiting relatives in Baltimore. (Union Academy said it plans to hold a press conference on Monday morning about the case.)

Soon after Barnes vanished, Baltimore police alerted local media, saying her disappearance was unusual because she had no history of disputes with her family or trouble with the law. Police called it one of the strangest and most vexing missing persons cases they had investigated, and, despite getting help from the FBI, they had few leads.

Police spokesman Anthony Guglielmi began describing it as "Baltimore's Natalee Holloway case."

Police worked to keep the search public, posting a photo of a smiling Barnes from her Facebook page on electronic billboards along highways in the Baltimore region. The effort spurred scores of tips, but none panned out.

More than 100 police officers combed a northwest Baltimore park in the weeks after she vanished, but found no clues to her whereabouts. Earlier this month, hundreds of law enforcement officers and volunteers searched a state park south of Baltimore and leafleted the area of the city where she was last seen. That daylong effort again failed to turn up any clues and police said they were "back at square one."

Then, two bodies were discovered Wednesday in the Susquehanna River near the Conowingo Dam, which is about an hour north of where Barnes was last seen. The distance between the locations where the two bodies were found is between three and four miles, police said.

A tattoo on one of the bodies grabbed investigators' attention because Barnes had a tattoo on her lower right leg. Dental records were used to positively identify the 16-year-old, police said.

It’s possible that Barnes’ body has been in the river since shortly after she disappeared and was only recently stirred up by warmer weather and storms, police said.

“We've had a cold winter, and when you put a body in a cold body of water, it will stay pretty much intact for a long period of time,” said Col. Terrence Sheridan with the Maryland State Police.

Barnes' cause of death is not yet known. There were no signs of injury or wounds to Barnes when her body was found, Sheridan said. Neither body had clothes on.

The medical examiner is doing more tests and forensic exams to determine how the teenager died, according to police.

Phylicia Barnes’ father, Russell Barnes, said he hopes to find out exactly what happened to his daughter.

"This is pretty much the first step," he said. "Our goal is to find out what happened. Why was Phylicia there, and what happened to Phylicia?"

Police said the news was difficult to break to the teenager’s family.

“It's horrible,” said Commissioner Fred Bealefeld with the Baltimore State Police. “It's the worst possible news you could give to any mother, and it's the last bit of news they ever wanted to hear."

The man's body recovered from the river has not been identified, but police said he was around 6 feet 4 inches tall and weighed around 240 pounds.

Baltimore city police and Maryland State Police are moving forward with a massive joint investigation to figure out what happened.

"Our goal simply is to bring closure to the Barnes family and figure out what happened and hold those responsible accountable," Bealefeld said.

Detectives retrieved fingerprints from the man's body and are running them through state and federal databases. Investigators are also planning searches in the area where the bodies were found in hopes of discovering additional evidence.

“We’re not going to spare any expense to try to find out what happened to these two people,” Sheridan said. "It's going to take a lot of work."