He's 41, has an extensive criminal record and served time in prison, according to online inmates records. He's on probation. Giroux used to have tattoos indicating white supremacist beliefs on his face but apparently had them removed, according to photos.
One thing investigators don't know: What caused Giroux to allegedly go on a deadly rampage.
On Thursday morning, Giroux made his first court appearance. He faces multiple charges, including murder, armed robbery with a deadly weapon, kidnapping, aggravated assault and burglary.
The prosecutor requested $2 million bond and the judge imposed it.
Grioux has been sent to prison twice for felonies, including an attempt to commit aggravated assault.
He was sentenced to seven years and six months behind bars in July 2007, but was released in October 2013, according to online inmate records. His probation runs through October 2016.
He also had a run-in with authorities in Santa Monica, California.
He allegedly committed assault with a knife in the early morning hours of March 26, 2006, and was detained by witnesses, said Santa Monica Police spokesman Sgt. Rudy Camarena.
Giroux was arrested on accusations of attempted murder and parole violation, but police records weren't immediately clear on how the case was resolved, Camarena said Thursday.
Police are looking for a motive in the first shooting on Wednesday, but say the other violence happened as the suspect tried to rob people and get away from authorities.
The first shots were fired after the suspect got into an argument at the Tri-City Inn with three people that he likely knew, according to Det. Esteban Flores of the Mesa police.
One man shot at the Tri-City Inn died, Flores said. Police identified him as David James Williams, 29, reported CNN affiliate KNXV
. The motel is across the street from the East Valley Institute of Technology
According to a police press release, the suspect next shot a man during a carjacking at a nearby restaurant and drove away in a stolen Honda Accord.
Grioux tried to carjack another vehicle but failed, police said, and crossed the street to break into an apartment, where he shot and tried to rob a fifth person.
He went to another apartment complex and shot a sixth person, police said, before fleeing to a condominium complex.
Flores said Mesa's SWAT team found Grioux in a vacant second-floor condo. Police used a Taser stun gun to subdue him.
Police said one man is in critical condition at a hospital, KNXV reported. The other victims, including the mother of the slain man, were treated and released from hospitals, KNXV reported.
Authorities on Thursday released a photo of a bruised Giroux in which he had a tattoo on his neck but no tattoos on his face.
An Arizona Department of Correction's photo released earlier showed a heavily tattooed Giroux, with the words "Skin" and "head" tattooed over his eyebrows. The number 88 was on his left temple, with additional ink on his chin and neck.
"Those are typical tattoos that you do see sometimes on white supremacists, but we don't know if that has anything to do with what happened today," Flores said.
Neo-Nazis use the number 88 as an abbreviation for "Heil Hitler." H is the eighth letter in the alphabet, so the Nazi salute becomes 88 in shorthand.
Flores said he believes all of the shooting victims were white, with one being white and of Hispanic descent.
"I have no information that his (Giroux's) affiliations or beliefs had anything to do with what occurred today," Flores said.
News of the shootings caught the attention of the state's senior U.S. senator.
"My thoughts and prayers are with the victims and families impacted by the tragedy in Mesa today," U.S. Sen. John McCain said in a statement
released Wednesday. "Our deepest thanks are with the Valley police and first responders who assisted the victims and tracked down the perpetrator to bring this dangerous situation to an end."
Mesa is about 20 miles east of Phoenix and is Arizona's third-largest city.