1. News
  2. /
  3. Hillsborough

Man accused in HART driver slaying found mentally incompetent

Justin McGriff will be transferred to Florida State Hospital to be treated and, if possible, made competent to stand trial.
In this image from the Hillsborough State Attorney's Office killer Justin McGriff is seen just prior to slashing the throat of HART bus driver Thomas Dunn, prosecutors say. [PHOTO COURTESY OF HILLSBOROUGH S | Photo courtesy of Hillsborough S]
Published Aug. 23

TAMPA — A man accused of slitting the throat of a public bus driver as he drove down Nebraska Avenue is not mentally competent to stand trial, a judge ruled Friday.

Circuit Judge Christopher Sabella issued the ruling after reviewing the findings of two court-appointed experts who evaluated Justin McGriff, a 36-year-old Tampa man charged with first degree murder in the May 18 slaying of Hillsborough Area Regional Transit Authority driver Thomas Dunn.

Prosecutors are seeking the death penalty.

Psychologists Jennifer Barror-Levine and Fred Farzanegan were tasked with determining whether McGriff “has sufficient present ability to consult with the defendant’s lawyer with a reasonable degree of rational understanding and whether the defendant has a rational, as well as factual, understanding of the proceedings,” according to a judge’s July order appointing them.

Sabella ordered McGriff transferred to Florida State Hospital in Chattahoochee to undergo treatment and make him competent to stand trial, if possible.

Bus driver Thomas Dunn speaks about driver safety at a Hillsborough Area Regional Transit Authority board meeting in December. Dunn, a 46-year-old U.S. Air Force veteran, was killed May 20 by passenger Justin McGriff, who slit his throat as he drove the MetroRapid bus down Nebraska Avenue, police said. [TONY MARRERO | YouTube]

According to testimony and footage and audio captured by the bus’s surveillance system, McGriff walked from the back of the bus clenching a knife in his hand and spoke briefly to Dunn as he drove south on Nebraska near Linebaugh Avenue.

“God bless you,” McGriff said

"What was that?" Dunn said.

"God bless you," he said again.

"Thank you," Dunn said. "God bless you, too."

McGriff then lunged forward, slitting Dunn’s throat, prosecutors say.

PREVIOUS COVERAGE: Slain HART driver chose busy route because he ‘loved people,’ friend says

Dunn steered the bus to the right and began to slow down as he slumped against his seat belt. McGriff moved to the door, looked back at the driver, then forced his way out. Tampa police officers arrested him a short time later after a brief foot chase.

Dunn, 46, died on the bus shortly after the attack.

Prosecutors have said the attack appears to be random. Court records show that people who knew McGriff told police he had been behaving erratically for several days before the killing.

Justin Ryan McGriff, 36, is seen in his booking photo taken on May 20. [TONY MARRERO | Tampa Police Department]


  1. John Jonchuck returned to a Pinellas County courtroom last month to attend a hearing about whether he was entitled to a new trial. A judge on Tuesday ruled that he is not. SCOTT KEELER  |   Times
    Jonchuck was convicted of first-degree murder in April. He dropped his 5-year-old daughter, Phoebe Jonchuck, off a bridge in 2015.
  2. Ralph Lewis Wald and wife Johnna Lynn Flores leave the Orient Road Jail on May 30, 2013, after Wald was acquitted in the fatal shooting of his wife's lover. [TIMES (2013)]  |  Tampa Bay Times
    An unidentified woman is found dead at their Brandon house. At the same time, the medical examiner confirms the wife has died.
  3. Eboni Wiley, left, testifies Monday in the murder trial of ex-boyfriend Granville Ritchie. Wiley was supposed to be caring for 9-year-old Felecia Williams the day the girl disappeared. OCTAVIO JONES  |  Times
    Eboni Wiley testifies that she’s telling the truth now about events surrounding the 2014 disappearance of Felecia Williams.
  4. Tampa police found Donta Allen, 33, in the area of E Palifox Street near N 44th Street at about 9 p.m. Sunday. He was suffering from upper body trauma and died later in a hospital. [TAMPA POLICE DEPARTMENT]  |  Tampa Police Department
    Police are seeking information from anyone who may have seen Donta Allen, 33, on Sunday night near the Tampa office center.
  5. Old Augusta bricks pave the road on West Bay Street in the Spanishtown Creek section of Hyde Park. ALLIE GOULDING  |  Times
    The neighborhood association wants the city to promise via an ordinance to not remove their community’s historic street bricks.
  6. A study found that two of the worst intersections in the country for running red lights are in the Tampa Bay area. Tampa Bay Times
    Two intersections are among the worst for running red lights
  7. Check for the latest breaking news and updates. JAMAL THALJI  |  Tampa Bay Times
    The Hillsborough County Sheriff’s Office believes the man tried to kill the woman, then shot and killed himself.
  8. Eboni Wiley, left, testifies at the trial of her ex-boyfriend Granville Ritchie who is accused of raping and killing 9-year-old Felecia Williams in 2014. Wiley led the girl to Ritchie, according to the state. Hillsborough Assistant State Attorney Jennifer Johnson, right, questions Wiley in a Hillsborough County Courtroom.Octavi OCTAVIO JONES  |  Octavio Jones
    Eboni Wiley was a friend of Felecia Williams’ family. She told jurors how she brought the girl to the man standing trial for raping and killing the 9-year-old.
  9. Check for the latest breaking news and updates. TMCCARTY  |  times staff
    The Hillsborough County Sheriff’s Office said it is obtaining a search warrant to start looking for evidence inside the house.
  10. Frank Joseph Fischer, 35, was arrested early Monday after he plowed into the back of a motorcyclist on Interstate 75 in Gibsonton, then kept driving, according to the Florida Highway Patrol. The motorcyclist, a 23-year-old Riverview man whose name was not immediately released, died at the scene. [Hillsborough County Sheriff's Office] Hillsborough County Sheriff's Office
    Frank Joseph Fischer, 35, was charged with DUI manslaughter and leaving the scene after driving his pickup into the back of the motorcycle, troopers said.