DOUGLAS COUNTY, Colo. — Questions remain days after an Iraq War vet emptied more than 100 rounds while firing a rifle at Douglas County officers in an ambush-style attack inside a unit at Copper Canyon apartments.

Douglas County Sheriff’s Deputy Zackari Parrish, 29, was killed and four others were injured in the New Year’s Eve attack. The 37-year-old shooter, Matthew Riehl, was shot and killed by police.

As Douglas County investigators piece together the events that led up to the shooting, more details concerning the shooter’s history have begun to emerge.

Riehl escaped from a veterans mental health ward in 2014 during a multi-week stay for a psychotic episode, according to the U.S. Department of Veterans Affairs.

Estranged from family and friends, he appeared to be spiraling out of control as he struggled to deal with a host of mental health issues leading up to the attack, according to recent police reports.

He was contacted by local law enforcement on multiple occasions months before the shooting, but it seems very little could have been done to stop Riehl. And it's still unclear whether his problems were grave enough to legally disqualify him from buying a weapon.

Riehl entered into the United States Army Reserves in 2003 and served in the Wyoming National Guard starting in 2006. Riehl was deployed to Iraq in 2009 and was honorably discharged in 2012.

Officials with the U.S. Department of Veterans Affairs said they have no psychiatric care history for Riehl until April 2014, when he experienced a psychotic episode and was hospitalized in Sheridan, Wyoming for three weeks. He was then transferred to a facility in Rawlings. Riehl later moved to Colorado and transferred his mental health care to VA Eastern Colorado.

During his hospitalization in Wyoming, Riehl “escaped/eloped from the Mental Health Ward, was located and brought back, and placed on a 72 hour mental health hold,” according to a new report provided to Congress by the U.S. Department of Veterans Affairs.

The suspect’s brother told University of Wyoming Police that Riehl was diagnosed with bipolar disorder and had recently suffered a “manic breakdown,” refusing all contact with family.

On July 22, 2015, the VA reports an urgent contact for mental health care for Riehl, with an initial mental health assessment completed August 26, 2015. The veteran was on multiple medications from a previous hospitalization, the VA notes.

On January 10, 2016, VA Eastern Colorado notes Riehl has an outside prescriber through Kaiser and is no longer requesting mental health services through the VA. He was scheduled to return on July 28, 2016, but it’s unclear if he made the appointment.

The agency declined to say whether that treatment meant Riehl should not have been allowed to own a gun.

Riehl was licensed as a lawyer for five years in Wyoming and voluntarily gave up his license in 2016, said Wyoming Bar Association executive director Sharon Wilkinson.

He practiced at a law firm in the small city of Rawlins and later opened his own practice but withdrew from the bar in October 2016, making him ineligible to practice law in the state, Wilkinson said.

Riehl earned his law degree from the Wyoming College of Law from the University of Wyoming in Laramie. He graduated from the College of Law in 2010 and made the Honor Roll in 2007.

One of his former classmates described Riehl as a guy who fed on conflict, a person who went to parties in college and picked fights — and usually got beat up.

His history at the school includes an alleged harassment incident in 2008 in which he’s accused of placing a bag of feminine hygiene products and a disparaging letter on the desk of a faculty member.

In October of 2017, years after graduation, Wyoming College of Law students had been warned about the former student because of his social media posts critical of professors at the school in Laramie.

One of the Facebook posts that led to the complaint was a photo of a courtroom with the name of a faculty member over it. The caption read “shot that motherf—ker dead on the streets of Laramie,” according to a University of Wyoming Police report obtained by Denver7.

During the investigation, police talked to Riehl’s mother in an attempt to locate the suspect. The mother told police she had not seen her son for some time, but he was emailing her frequently. In one of many inflammatory emails to his mother, Riehl accused her of being a “tranny prostitute,” the report reads.

The mother told police Riehl might be living at his Lone Tree, Colorado home. She told them she was concerned because he had post-traumatic stress disorder from his 2009 deployment to Iraq and was refusing to take his medication to treat it, a statement backed up by several of the suspect’s friends who were interviewed as part of the University of Wyoming investigation.

She stated she wanted authorities to locate him and help him get treatment. According to the report, her attempts to get Lone Tree Police to help her son were unsuccessful. She acknowledged her son had not yet threatened anyone with bodily harm.

After interviewing Riehl's mother, university police reached out to investigators at the Lone Tree Police Department to share their concerns and learn more about any possible contacts the department may have had with the suspect.

A LTPD detective told them they had recently filed a false reporting case against Riehl for a claim made by the suspect in which he said his mother and brother had entered into a suicide pact, and they were going to the kill themselves, according to the university's report.

The Lone Tree Police department had also made numerous welfare checks at the suspect’s home, but Riehl would not let officers in, according to the police report. In November, Lone Tree Police issued a statewide bulletin on Riehl so other officers in the state would be made aware of the situation, the report reads.

The following incident reports were provided by the Lone Tree Police Department:

June 9, 2016: LTPD responded to a family disturbance at a Lone Tree residence where Riehl was in an altercation with his father. Family did not press charges and Riehl left for the night.

February 18, 2017: Riehl was issued a citation for careless driving for a traffic accident he was involved in.

June 8, 2017: LTPD conducted a welfare check at a Lone Tree residence when Riehl’s mother asked police to check on him due to concerns over his mental health. Officers spoke to Riehl for almost 14 minutes through a closed door as he would not let them in. He stated repeatedly he was not a danger to himself or others, and officers had no probable cause or information to force the issue. Mental health service information was provided to the suspect and his family, but they denied services offered.

August 16, 2017: Riehl called in a welfare check stating that his mother and brother made a suicide pact and were a danger to the community. Officers responded to the residence and found this to be untrue. During this visit, LTPD learned from the mother that Riehl had moved out of the house a month prior and was staying in Rawlins, Wyoming. Due to a lack of probable cause, there were no charges filed against Riehl over this incident.

November 10, 2017: A LTPD officer issued Riehl a speeding ticket in the City of Lone Tree, which resulted in a court summons.

November 14, 2017: A detective with the University of Wyoming Police Department reached out to LTPD regarding Riehl and social media posts that the suspect had made that were possibly threatening to the university.

During the month of November, the suspect also shared posts on his social media account about a specific LTPD officer and a citation he had received on Nov. 10. His behavior escalated to include harassing e-mails directly to LTPD police officers. Since LTPD confirmed that Riehl now resided at an address in unincorporated Douglas County and his posts directly involved a LTPD officer, LTPD contacted Douglas County Sheriff’s Office (DCSO) to investigate, and provided all available information and reports regarding Riehl.

Riehl was also active on YouTube, posting several telling videos.

In a clip posted on the video-sharing website a few weeks ago, Riehl calls for the firing of Douglas County Sheriff Tony Spurlock and rails against him in highly personal terms.

In the same video, he is also seen holding up a deputy's business card and accusing the deputy of being a pimp.

"The pimp will then ambush you from behind the door," Riehl is heard saying in the video, which has since been removed from the site.

Denver7 has also learned that the shooter live-streamed his confrontation with deputies online on Periscope.

"Maybe I bought over 1,000 rounds of ammunition from Walmart. It's not illegal," he says.

Later, he tells a police dispatcher that a man had invited him to his house and was acting strangely.

When authorities arrive at Riehl's unincorporated Douglas County apartment, the footage shows him talking to at least two officers, telling them he wants to file an emergency restraining order against his domestic partner. He is upset when one officer gives him a phone number to call, and leaves the doorway to go back into a room.

"Did you not get the message? Wow. They didn't get the message. They lied," he is heard saying on the video.

At another point, Riehl is seen holding a glass in his hand and says he's had two scotches. He is heard saying that drinking would help him defend himself if someone bothers him.

In the graphic video clip published on the website LiveLeak, Riehl can be heard yelling at first responders before opening fire.

"Go away... go away... don't come in... I warned you," the voice yells, before loud shots can be heard.

"What? Get the f--k out of here! Why are you here? You don't have a warrant! Go away.... leave me alone... get out," before more shots are heard.

The entire audio clip is only about a minute long.

Sources tell Denver7 Investigates that the shooter did live stream the incident, and that the video is being compared to officer body camera footage as part of the investigation.

3 a.m.: Douglas County dispatch received a call reporting a verbal disturbance at the Copper Canyon apartments. Deputies responded to the scene and spoke with two men. One man claimed the other, Matthew Riehl, was acting strangely and seemed to be having a mental breakdown.

3:44 a.m.: Deputies left the apartment when they could find no evidence that a crime had been committed.

5:14 a.m.: Deputies were called back to the scene.

5:17 a.m.: The first deputy arrived at the apartment complex.

5:35 a.m.: Three additional deputies arrived at the apartment complex. They were given the keys to Riehl’s apartment and given permission to enter.

5:56 a.m.: Riehl opened fire with a rifle after barricading himself inside his bedroom, hitting all four deputies. Officers backed out of the apartment. However, Deputy Parrish was not able to retreat. He had been hit multiple times and stopped responding to radio calls. He passed away. Deputies Michael Doyle, Taylor Davis, and Jeffrey Pelle were also shot.

7:30 a.m.: SWAT entered the apartment and exchanged fire with Riehl. Officer Thomas O’Donnell was shot. The suspect was killed.

Two people in nearby apartment units were also wounded sometime during the prolonged standoff.

The Associated Press contributed to this report

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