Desertion is charged after the soldier has absented himself/herself from the unit for over 30 days.
A desertion charge doesn't mean the soldier will be tried for desertion, as the actual charge is up to the commanding officer and/or the General Officer who actually prefers charges.
The reason the soldier must be absent for over 30 days is so the army can inform the civilian authorities via NCIC, which allows civilian law enforcement personnel to "hold" the soldier until the nearest military police can pick up the individual and return the soldier to the base where the soldier is assigned.
Desertion is dealt with more aggressively during war time, because if it weren't, many service members would absent themselves from their unit to avoid being forward deployed.
If it were during war time operations, missing shipment or movement is often also charged, upping the ante at trial.
As regards the soldier referenced above, El Paso PD were unable to confirm the person did the things he alleged he did.
In mid-September, El Paso Police Department officials said in a statement carried by local media that they had no independent confirmation of Oakley's actions after reviewing surveillance footage from the scene of the shooting.
El Paso police question second El Paso shooting heroism story
EL PASO, Texas (KFOX14) — Police are disputing a second story of heroism during the Aug 3. mass shooting.
The day after the shooting, a Fort Bliss soldier, Pfc. Glendon Oakley, told a very emotional story about allegedly carrying children out of the Cielo Vista Mall, located next to the Walmart.
Since his story was told, no one has been able to verify if it's true.
KFOX14 asked police if surveillance footage from the mall showed Oakley carrying children out.
Police said that all surveillance footage is being used for the shooter's trial, therefore cannot be released. They said they are not discounting his story, but can't verify it.
Adding in a statement:
"We have no independent confirmation of that. All we can say is that there were reports of possible multiple shooters and a possible shooter at the mall. That was based on initial erroneous reports amidst the chaos. It was later confirmed that there was only one shooter and there was no one in danger at the mall. We have no independent reports of anyone's actions at the mall."
PFC Oakley wasn't the only "hero" whose exploits couldn't be verified or corroborated.

Chris Grant is seen in a hospital bed.
Police dispute El Pasoan's story of heroism during Walmart shooting
The army awarded the soldier with the ARCOM, which might lead to additional legal difficulties for the person.
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El Paso police question second El Paso shooting heroism story
Soldier praised as hero during El Paso shooting arrested after going AWOL
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