Dec. 29, 2013  -- The man suspected in a spree of bank robberies and the killing of a police officer in Tupelo, Miss., was sentenced in 2010 for threatening to kill President Obama and his predecessors, a federal law enforcement official told ABC News.

Authorities today identified the suspect, who was killed Saturday in a shootout with police outside a Phoenix, Ariz., bank, as Mario Edward Garnett, 40.

An indictment said that in August 2010 Garnett allegedly posted a message to the White House website, saying among other things: "if you order a strike on Iran, I'm going to come up there and blow your brains out on national TV. You scheming hypocrite ... Netanyahu is a dead man. Damn Israel."

Six days later, he allegedly posted another message, saying: "I'm going to settle some scores on behalf of Israel and America's victims on behalf of those they continue to oppress. I'll kill president and farmer alike. You are either worth something or you are chaff."

Garnett was sentenced in June 2011 to eight months behind bars and three years supervised release for the threats against the president.

According to court documents, he was held for a month after his sentencing, but on July 26, 2011, he was let out on supervised released.

He was supposed to participate in a "program of mental health aftercare," but he violated the conditions of supervised released, saying during a mental health session on Sept. 21, 2011, that his probation officer should be "put to death," according to the document.

He repeatedly "rants and makes threats," court documents said at the time.

A federal judge placed Garnett on home confinement with GPS monitoring for 120 days.

But in October 2011, a federal judge sentenced Garnett to 24 months in prison for violating his supervised release, and the judge said he "recommends a facility to evaluate and address the defendant's mental health."

Nationwide Manhunt Comes to End in Arizona Shootout

According to the FBI, Garnett -- armed with a gun -- entered a Phoenix bank around 10 a.m. on Saturday. After allegedly taking cash from the bank vault, the suspect attempted to flee, but then encountered a Phoenix police detective. Shots were exchanged and the suspect died from his wounds, according to the FBI.

The bank was the third known robbery or robbery attempt linked to the suspect within the last week, FBI officials said.

Officials had conducted a nationwide manhunt for the man after he allegedly shot two police officers following a bank robbery in Tupelo, Miss., on Dec. 23. One of the officers was fatally wounded.

A total reward of more than $200,000 had been offered to anyone with information leading to the arrest of the suspect.

FBI special agent Daniel McMullen said today the investigation was ongoing, but multiple clues led investigators to believe that Garnett is the same man responsible for the robbery and shooting in Mississippi.

According to police, cell phone records showed the suspect was in the same area as each different bank robbery and wore similar clothing during each robbery attempt. He also allegedly made similar statements at each robbery.

The suspect was also allegedly connected to an earlier robbery attempt in Atlanta. According to police, just hours before the fatal incident in Mississippi, the suspect unsuccessfully tried to rob a Bank of America with a gun. After initially failing, the suspect then walked outside and robbed a person at the ATM.

Vigil Held as Manhunt Goes Nationwide

At the news conference today, McMullen also revealed new details about the fatal Dec. 23 shooting in Tupelo. According to police the suspect fled the Tupelo bank in a grey sedan, but was later reported to be in a white SUV.

When the two officers, Gale Stauffer and Joseph Maher, responded to the bank alarm, they saw a white SUV near the bank and stopped the vehicle. The suspect was in a grey sedan behind the SUV. While the officers were dealing with the driver of the white SUV, the suspect ambushed the two officers, fatally wounding Stauffer.

At the press conference today, Stauffer's wife, Beth Stauffer thanked law enforcement officials for their hard work.

"Numerous people did not get to celebrate Christmas with their families, because they were trying to bring peace to our family," said Beth Stauffer.

Earlier this week residents in Tupelo held a candlelight vigil for Stauffer.

Flags were lowered to half-staff in memory of Stauffer, an army veteran of the Iraq War, and father of two young children.

"I'm at peace knowing Gale died doing what he loved," his wife said.

Stauffer was a combat veteran of the Louisiana Army National Guard, and he had served with the Tupelo Police Department for eight years, according to the Officer Down Memorial Page.

ABC News' Mike Levine and Ben Krolowitz contributed to this report.