A Tennessee Army veteran is being charged with first-degree murder and assault in what authorities say were two separate attacks on men experiencing homelessness in less than a week.

The most recent attack happened just before 3 a.m. on May 31 when police responding to 911 calls found a man suffering from gunshot wounds outside a Courtyard by Marriott hotel in Memphis. The man, identified as Shaun Rhea, died at a hospital, according to court records obtained by USA TODAY on Wednesday.

The first attack happened just six days before Rhea's killing at the same hotel on May 25. A man told police that he was inside a portable bathroom outside the hotel where he sleeps each day when an assailant began grabbing at him, put a knife to his face and cut him behind his left ear as he tried to flee. The attacker also cut him on his right thumb.

Here's what we know about the crimes and the veteran who was charged with them on Tuesday.

Shaun Rhea killing

A security guard told police he saw a man who had a knife pepper-spraying Rhea the day of the fatal shooting. The security guard recorded the attack on his phone and told the attacker what he was doing in hopes that he would leave, court records say.

The attacker ran to an apartment, allowing Rhea to clean the spray off his face. But soon after that, the attacker returned with a rifle and shot Rhea multiple times, court records say.

Investigators looked at mailboxes at the apartment building where the attacker was last seen and found the name Karl Loucks. The security guard looked at a six-person lineup and identified Loucks as the man who shot Rhea.

Loucks, 41, was arrested the same day.

While in court on Tuesday, Memphis police Sgt. Jeremy Cline said Loucks was interviewed after his arrest and told investigators he was acting in self-defense, according to WTVC-TV.

“Shaun Rhea was unarmed at the time of the assault,” court records say.

Loucks' lawyer, Blake Ballin, declined to comment on the case when reached by USA TODAY on Wednesday.

First attack on an unhoused person

In the May 25 attack on an unhoused man, the assailant also fled to an apartment complex.

The victim got stitches at a local hospital. He later told police that he did not know his attacker.

After Loucks' arrest in Rhea's killing, the May 25 victim identified Loucks as being the man who attacked him.

Who is Karl Loucks?

Loucks is a U.S. Army veteran who served in the war in Afghanistan, Army spokesman Bryce Dubee told WTVC-TV. He was a healthcare specialist in the Army from September 2007 to August 2013 and served in Afghanistan from March 2009 to March 2010, the outlet reported. 

Loucks left the Army with the rank of private first class and was honorably discharged due to post-traumatic stress disorder, his lawyer told the outlet. 

Ballin, Loucks' lawyer, told WTVC that he is trying to schedule a psychological evaluation to see if Loucks' mental health had anything to do with the shooting.

“If somebody in Mr. Loucks' situation, with his experience in the past, his experience in these events, felt reasonably that he was in fear for his life or his physical safety, then he may have been justified in acting the way he did,” Loucks’ lawyer told the outlet.

Shelby County Judge Bill Anderson, who is overseeing the case, said Loucks' history with the Army may have played a role in what happened.

“Some cases don't make any sense, any logical sense,” Anderson said. “This is one of them.”

Saleen Martin is a reporter on USA TODAY's NOW team. She is from Norfolk, Virginia – the 757. Follow her on Twitter at@SaleenMartin or email her at[email protected].