Spc. Iván López was already upset that he had only been granted less than two days to attend his mother's funeral last year.

So a dispute over his second request for a leave apparently was the spark that led López on a shooting spree at Fort Hood in Texas that left three people dead and 16 injured last Thursday.

The rampage has now shone a spotlight on the military's policy on leaves, which can sometimes be an arbitrary process that can breed resentment.

U.S. Army spokespeople have not publicly commented on a claim by the family that he was only granted 24 hours to go to Puerto Rico after his mom’s death. That leave was later extended to two days. Army officials have also not said whether last Thursday's request was granted. Army spokesman Chris Grey said only that López was “involved in a verbal altercation concerning his request for leave and the processing of that request at his unit’s administrative office.”

Whether a leave is granted is up to the discretion of the soldier’s commander, say former Army leaders and representatives of organizations concerned with soldiers’ rights.

Members of the military get 30 days of ordinary leave every year, and the death of a close relative counts as “emergency” leave which is usually granted without much issue. Often, the American Red Cross acts as “the conduit of information between the U.S. military and family members of servicemen,” the group’s communication director for service to the armed forces, Peter Macias, told Fox News Latino.

Especially with personnel in far-flung locations, the family may first alert the Red Cross about a death. “We extract a lot of the information and verify it,” Macias said. “Then share it with the military. Once we deliver the information, our hands are off the process.”

“Sometimes the serviceman alerts his military command—it happens in both directions,” said Joe Davis, a national spokesman for the Veterans of Foreign Wars in Washington, D.C.

“With the death of an immediate member of the family,” retired general John Keane told Fox News Latino, “we were always pretty liberal about the amount of time the soldier got. We’d bring him home out of combat if we had to.”

But how much leave a soldier gets is ultimately up to their boss.

“As at any job, there are good supervisors and bad supervisors,” the VFW’s Davis said. “Sometimes they believe the serviceman without question—sometimes they ask for a death certificate. But the length of the leave is based on the commander’s decision.”

The encyclopedic “Leaves and Passes” section of the Army regulations doesn’t specify a length of time for leaves, be they bereavement or otherwise.

According to a Department of Defense instruction document on “Leave and Liberty Policy and Procedures” dated June 2009, “Commanders may authorize up to 30 days of emergency leave.”

The document goes on to say that “swift and sensitive action on emergency leave requests is essential. Nevertheless, care must be taken to ensure that an emergency does exist and that the Service member’s presence can resolve or alleviate the situation.”

Other requests for emergency leave that don't involve the death of a family member are less automatic, according to sources, and is even more at the discretion of commanders. If for some reason, Spc. López's superiors had reasons to be skeptical of his request for emergency leave when his mother died, subsequent requests by the Army specialist may well have been met with even greater skepticism.

The public may never know the details of the dispute that may have set off López, why he was only granted a few days leave after the death of his mother or whether that is indeed the reason he went on a mass shooting at the Army base.

"What a terrible tragedy," VFW spokesman Davis said. “I’m sure that the leaders at Fort Hood are asking themselves all those questions.”

Bill Vourvoulias (@bvourvoulias) is an editor at Fox News Latino.

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