Here is some background information about recent soldier on soldier attacks in the U.S. military.
November 12, 2009 - Hasan is charged with 13 counts of premeditated murder.
December 2, 2009 - Hasan is charged with 32 counts of attempted premeditated murder.
July 6, 2011 - Lt. Gen. Donald M. Campbell Jr. refers Hasan's case to a general court-martial and rules that he is eligible for the death penalty.
July 20, 2011 - Hasan is arraigned.
June 8, 2012 - Col. Gregory Gross reschedules Major Hasan's hearing. The decision is made by the judge after Hasan shows up in court with a beard, which is in violation of military regulations.
August 17, 2012 - A military appeals court halts the murder case against Maj. Nidal Hasan indefinitely, to determine whether the Army can forcibly shave Hasan's beard during trial.
October 18, 2012 - A military appeals court decides that Hasan can be forcibly shaved, despite his assertion that his religion requires he wear a beard.
November 19, 2012 - The U.S. government asks a military appeals court to deny Hasan's request to keep his beard and to reject the defense motion to remove Col. Gregory Gross as the judge overseeing the court martial proceedings.
December 3, 2012 - A military appeals court removes Col. Gregory Gross as the judge in Maj. Nidal Hasan's court-martial, saying he is biased. The ruling makes the judge's order for Hasan's beard to be shaved invalid.
December 4, 2012 - Col. Tara Osborn is appointed as the new judge in Hasan's case.
June 3, 2013 - Col. Tara Osborn rules that Hasan is physically fit to represent himself during his court-martial. Hasan was shot and paralyzed from the chest down on the day of the massacre in which he is accused of killing 13 people. He can only sit for limited periods of time.
August 6, 2013 - Hasan's court-martial begins. During opening statements, Hasan declares, "The evidence will clearly show that I am the shooter."
August 23, 2013 - A military jury convicts Hasan of 13 counts of murder and 32 counts of attempted murder in a shooting rampage at Fort Hood, Texas, making it possible for the death penalty to be considered as a punishment.
August 28, 2013 - After less than two hours deliberating privately, the 13-member panel recommends the death penalty for Hasan.
Timeline of Other Recent Soldier on Soldier Attacks:
October 27, 1995 - Sgt. William Kreutzer, using a sniper rifle, kills one soldier and injures 18 others at Fort Bragg in North Carolina. He is sentenced to death in 1996. In 2009 he is resentenced to life in prison.
March 5, 1996 - Marine Sgt. Jessie A. Quintanilla shoots and kills his executive officer, Lt. Col. Daniel W. Kidd, then shoots and seriously wounds his commanding officer, Lt. Col. Thomas A. Heffner, at Camp Pendleton in California. He is convicted and sentenced to death. His death sentence is reduced to life in prison in 2010.
March 23, 2003 - Army Sgt. Hasan Akbar launches a rifle and grenade attack on officers' tents at Camp Pennsylvania in Kuwait, during the first days of the Iraq War. Two officers are killed and 14 others are wounded. In April 2005, he is convicted and sentenced to death.
September 14, 2008 - Army Sgt. Joseph Bozicevich shoots and kills Staff Sgt. Darris Dawson and Sgt. Wesley Durbin at Jurf as Sakhr, Iraq - a joint U.S.-Iraqi patrol base south of Baghdad. After being found guilty of two counts of murder, Bozicevich is sentenced in August 2011 to life in prison without parole.
May 11, 2009 - Sgt. John M. Russell shoots and kills five service members at a mental health clinic at Camp Liberty in Baghdad, Iraq. In April 2013 Russell pleads guilty in exchange for prosecutors dropping the death penalty. He is sentenced to life in prison in May 2013.
September 24, 2010 - Spc. Neftaly Platero shoots two fellow soldiers serving at Camp Fallujah in Iraq, and wounds a third during a verbal altercation. In 2012 Platero is convicted of the murders of Spc. John Carrillo Jr. and Pfc. Gebrah P. Noonan and sentenced to life in prison.
April 2, 2014 - Army Specialist Ivan Lopez, an Iraq war veteran, kills three people and injures 16 more at Fort Hood, Texas. He then kills himself.