TAMPA, Fla. (WFLA) — The man convicted of murdering a HART bus driver in 2019 learned his fate Wednesday.

Justin McGriff will spend the rest of his life behind bars for the deadly attack.

In court, prosecutors read a letter written by Thomas Dunn’s brother, who was too emotional to face his killer.

“More than one person died that day. Thomas Dunn was more than one person and will continue to be missed and grieved by many,” the prosecutor read.

According to officers, McGriff had been arguing with Dunn before the stabbing. Afterward, witnesses told police McGriff got off the bus and ran toward I-275. He was later captured and charged with first-degree murder and resisting arrest without violence.

McGriff was convicted for stabbing Dunn to death in front of horrified passengers in 2019.

McGriff was declared incompetent at one point before the trial. Before handing down his sentence, the judge addressed what he called a national mental health crisis.

“It is sad our mental health system has failed us,” the judge said.

Dunn was a father and a veteran, who had fought for bus safety changes before his death. Dunn’s former co-workers were also at the sentencing to show their support.

“Thomas was a good guy. He was my coworker and friend, and he didn’t deserve it,” said fellow driver Angela Read.

Less than a month after Dunn’s death, the Pinellas Suncoast Transit Authority (PSTA) took action and announced new safety barriers with extended tempered glass to protect drivers. About a week later, HART announced similar safety barriers would be installed on all HART buses and HARTFlex vans.

Dunn’s former colleagues say those changes don’t go far enough.

“That doesn’t stop this from happening. It’s still happening, and we’re here to make sure that justice is served,” said Ismael Rivera.

The judge handed down a mandatory life sentence for McGriff.

McGriff did not have any family in the courtroom and did not appear to have any reaction to the sentence.

“It’s not enough,” said Dunn’s brother Michael. “It’s just good to know he won’t be out to hurt anybody else.”