(Reuters) - The Federal Bureau of Investigation said on Thursday it would review the hanging death of an 18-year-old black Washington teen that was initially ruled a suicide, after a Muslim civil rights group raised questions about the investigation.

The body of Ben Keita, who was Muslim, was found hanging from a tree in January in a wooded area in the city of Lake Stevens, Washington, about 30 miles north of Seattle, according to police. Keita had been reported missing in November.

In a Jan. 10 autopsy, the medical examiner determined Keita’s cause of death as strangulation, apparently as a result of suicide, Kent Patton, a spokesman for the Snohomish County Medical Examiner’s office, said in a telephone interview.

A week later, after speaking with Keita’s family members, the medical examiner determined that there was not enough evidence to reach that conclusion and changed the manner of death to “undetermined,” Patton said.

Police searched the area around the Keita family’s suburban home three times between Nov. 30 and Dec. 7, using dogs and a helicopter in futile attempts to find him, Arsalan Bukhari, executive director of the Washington State chapter of the Council on American-Islamic relations, said in a phone interview.

On Jan. 9, a group of young people who went into the wooded area near the Keita family’s home spotted the teen’s body hanging from a high tree.

The family became concerned that police had not been aggressive enough in investigating the death and decided the cause was suicide too quickly, even though previous searches of the area failed to find Keita’s body, Bukhari said.

“They were really concerned that it was not a comprehensive and diligent effort,” he said.

FBI spokeswoman Ayn Dietrich said in an email on Thursday that the agency had communicated with police and would review the circumstances of Keita’s death. “If warranted, we may conduct further investigation,” Dietrich said.

Lake Stevens police detectives said in a statement on Wednesday that they had conferred with the FBI and were keeping the case open while they awaited results from the Washington State Crime lab.

Keita was a student at Running Start, a college-level program for high school students at Everett Community College and worked at a McDonald’s restaurant, police said.