Jim Gibson

A friend of the Cleveland, Tenn., missionary shot to death Tuesday in Africa said he will withhold judgment about the claim that terrorist group al-Quaida was responsible for the killing until it can be validated.

"Maybe it is true, maybe it isn't," said the Rev. Jim Gibson, co-pastor of First Baptist Church of Cleveland, where Christopher Ervin Leggett was a member. "I don't think it would be very wise to address that until either it can be confirmed as true or false."

A branch of terrorist group al-Qaida on Thursday claimed responsibility for the death of Mr. Leggett, who was shot several times by unidentified gunmen.

Arab satellite TV station Al-Jazeera said it received an audio statement from al-Qaida's North Africa branch in which the group said it killed the 39-year-old for trying to convert Muslims to Christianity in Nouakchott, Mauritania, according to The Associated Press.

"Two knights of the Islamic Maghreb succeeded Tuesday morning at 8 a.m. to kill the infidel American Christopher Leggett for his Christianizing activities," the group said in the statement.

The authenticity of the statement could not be independently verified.

Mauritania's Interior Ministry said Thursday it was investigating the death, and security forces were doing "all they can to catch the criminals."

Mr. Gibson said the family is coping as best it can under the circumstances and appreciates the love and support of friends.

"The memory of Chris will impact a lot of people for a long time to come, and we're already seeing how that is beginning to happen and we're very thankful for that," he said.

Mr. Leggett; his wife, Jackie; and their four children had been living in the West African nation for six years. He performed humanitarian work while teaching at a school specializing in computer science.

Mr. Leggett's family said the U.S. Department of State and the office of U.S. Sen. Lamar Alexander, R-Tenn., were working to hasten the return of Mr. Leggett's body to Cleveland as early as Saturday. His wife and children also may return this weekend, according to reports.

"Sen. Alexander was deeply disturbed to hear of Mr. Leggett's murder, and his Chattanooga office has been in touch with the Leggett family in the aftermath of this tragedy," according to a statement released through the senator's press office.

The Associated Press contributed to this story.