Nidal Malik Hasan, the psychiatrist now charged with killing 13 people and wounding 28.

CNN: STORY HIGHLIGHTS

Nidal Malik Hasan -- the U.S. Army psychiatrist accused of fatally shooting 13 people at Fort Hood, Texas, on November 5 -- had exchanged e-mails.

CNN: STORY HIGHLIGHTS

Nidal Malik Hasan, was not cashiered out of the Army after a shocking June 2007 PowerPoint presentation he gave as part of his psychiatric residency program.

CENTERFORSECURITYPOLICY: Center For Security Policy

Authorities say Nidal Malik Hasan, a U.S. Army psychiatrist, opened fire at a military processing center at Fort Hood on November 5, killing 13 people.

CNN: Purple Hearts proposed for Fort Hood victims

The perpetrator, Major Malik Nidal Hasan, appears to be a devout American-born Muslim, who grew up in Virginia.

CENTERFORSECURITYPOLICY: Hasan was not a ��sleeper,�� says forensic psychiatrist