Everything seemed normal with Joevon Smith-Patterson until the evening of Jan. 11, when he suffered a seizure and coughed up blood. The 17-year-old told his mother he had been attacked in his high school classroom the day before.

Relatives rushed the teen, a special-needs student, to a hospital and called D.C. police.

The Ballou High School senior later slipped into a coma and died Jan. 29. The medical examiner has not ruled on how he died or whether his death is linked to the apparent assault that Smith-Patterson had described. He and a witness told police that the altercation occurred Jan. 10 and was over the youth's reluctance to let his attackers use his cellphone.

D.C. police have assigned homicide detectives to the case, but they said it is a complex investigation. Statements from Smith-Patterson and a key witness conflict, and authorities have not been able to pinpoint a crime scene.

Police Chief Peter Newsham said investigators are reviewing security tapes and interviewing teachers, security guards and other students, some of whom also have special needs, to determine whether there was a crime.

Interviewing developmentally disabled students presents challenges, Newsham said, as investigators work to "get an accurate picture of what occurred."

Police said no one interviewed so far has been able to say what time the alleged attack happened. A police report says Smith-Patterson had no visible injuries, though he suffered headaches and nausea.

The District's school system has declined to comment on the investigation. In a letter to students following Smith-Patterson's death, Katreena Shelby, Ballou's interim principal, said it was "a devastating loss, and it is sure to raise many emotions, concerns, and questions from our entire school."

D.C. Council member Trayon White Sr. (D-Ward 8), a former community activist, said in a statement that Smith-Patterson's death was a "devastating tragedy" for the youth's family. He said Smith-Patterson ran track at Ballou and was set to graduate this year.

"Joevon's family is convinced that this incident happened inside the school by other students," White's statement says. "DCPS cannot confirm that the allegations are true at this moment. The Metropolitan Police Department is currently investigating this case and the cause of Smith's death."

Smith-Patterson's family is hopeful the medical examiner can provide some much-needed answers as the investigation continues. The teen's mother, Rashonda Smith, has said little publicly and referred a reporter to an attorney, who did not return phone calls to his office.

Smith-Patterson's cousin, Young Van, 32, described the teen as "definitely quiet" but also as talkative when among people he knew. Police said his delayed speech made it difficult for detectives to understand him.

"He was like a shy type of kid," Van said. "He never got into any trouble. He loved being around family. He never had any seizures until this incident."

According to a police report, Smith-Patterson told officers that two classmates struck him on the face and body while they were inside a classroom. He also told police that he was "sprayed about the body with 'perfume' by one of the suspects."

In a more detailed version of the incident obtained by The Washington Post, another student told police that Smith- ­Patterson was struck with a stun gun in the leg. But Smith-Patterson did not include a stun gun in his account.

"Neither student was able to give an accurate or approximate time of the offense," police wrote in a report, which was taken about 7:30 p.m. on Jan. 11.

Police noted that Smith-Patterson "was suffering from nausea, stomach aches, and headaches. Doctors were concerned about [his] medical results."

Authorities have identified three possible suspects. None could be reached for comment.

For Ballou, Smith-Patterson's death is yet another blow to a troubled institution. A recent report revealed the school had graduated students who improperly took makeup classes and missed large portions of the year. In addition, two students have been killed by gunfire this academic year.