TAMPA, Fla. — Opening statements began Wednesday in the trial of a man accused of murdering a HART bus operator.

Justin McGriff is in custody in the stabbing death of driver Thomas Dunn in May 2019.

Dunn had just begun his route near the VA hospital when he picked up McGriff and several other riders.

Nearly 13 minutes later, Dunn was stabbed.

In front of a seated jury, Dunn's family and McGriff, the state revisited Dunn's final moments and words.

Surveillance footage shows McGriff sitting in the back of the bus with his backpack beside him.

The state says he then pulls the knife out of his pocket and makes his way to the front of the bus and exchanges words with Dunn.

McGriff, who was 35 at the time, said “God bless you” twice before the attack.

He is then seen swinging the knife toward Dunn.

Detectives say Dunn was able to pull the bus over safely, despite his injuries.

McGriff was arrested a short distance from the scene and was charged with first-degree murder.

He won’t face the death penalty according to State Attorney Andrew Warren, who made that decision upon learning about McGriff's mental illness.

The state says that the murder weapon was never recovered.

The defense plans to call witnesses familiar to McGriff, including his mother and two sisters to the stand.

The state says it hopes to rest its case early next Friday.

Dunn was an Air Force veteran, husband and father. He was 46.

As a result of the attack, HART and the Pinellas Suncoast Transit Authority (PSTA) upgraded safety measures and installed driver barriers on buses.