WASHINGTON — The Army psychiatrist accused of the Fort Hood massacre is believed to have acted alone, despite repeated communications — monitored by authorities — with a radical imam overseas, U.S. officials said Monday.

The FBI will conduct an internal review of its handling of the information, the officials said.

An investigative official and a Republican lawmaker said Maj. Nidal Malik Hasan was in contact with Anwar al-Awlaki, an imam released from a Yemeni jail last year, 10 to 20 times. Despite that, no formal investigation was opened into Hasan, they said.

Investigative officials spoke on condition of anonymity because they were not authorized to discuss the case. Republican Rep. Pete Hoekstra of Michigan, the top Republican on the House Intelligence Committee, said it was his understanding Hasan and the imam exchanged e-mails that counterterrorism officials picked up.

Hasan, awake and talking to doctors, met his lawyer Monday in the Texas hospital where he is recovering under guard from gunshot wounds in the rampage Thursday that left 13 people dead and 29 injured. Officials said he will be tried in a military court, not a civilian one.

Rep. Jason Chaffetz, R-Utah, says he will attend the memorial service Tuesday at Fort Hood, Texas, to honor victims of the mass shooting. "It will be an honor to represent Utah and recognize our soldier who was killed," Chaffetz said in his Twitter account.

Pfc. Aaron Nemelka, 19, of West Jordan, was among those killed.

President Barack Obama is also scheduled to attend the service.

FBI Director Robert Mueller has ordered an internal inquiry to see whether the bureau mishandled worrisome information gathered about Hasan beginning in December 2008 and continuing into early this year.

Based on all the investigations since the attack, including a review of that 2008 information, the investigators said they have no evidence that Hasan had help or outside orders in the shootings.

Even so, they revealed the major had once been under scrutiny from a joint terrorism task force because of the series of communications going back months. Al-Awlaki is a former imam at a Falls Church, Va., mosque where Hasan and his family occasionally worshipped, and runs a Web site denouncing U.S. policy — a site that praised Hasan's alleged actions in the massacre as heroic.

Military officials were made aware of communications between the two, but because the messages did not advocate or threaten violence, law enforcement authorities could not take the matter further, the officials said. The terrorism task force concluded Hasan was not involved in terrorist planning.