LATEST: Man allegedly threatened  witness in 2012 high school student’s homicide

Sept 04, 2018
Joseph Thomas Diaz (Palm Beach County Jail)

Before Joseph Thomas Diaz took a gun from his waistband, placed the barrel against the woman’s face and then pistol-whipped her, he asked her if she knew someone, according to the Palm Beach County Sheriff’s Office. 

Frankie Quarles, you snitched on him,” he replied, according to the arrest report. “You are the reason my brother got 35 years.”

Diaz, 23, was arrested Monday and faces charges of aggravated battery with a firearm, robbery with a firearm, being a felon in possession of a firearm and retaliating against a witness. Palm Beach County Circuit Judge Dina Keever ordered Diaz to be held without bail Tuesday morning during a hearing in the courtroom at the Palm Beach County Jail. 

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Frank Quarles, 22, was sentenced to 35 years in prison in April for the 2012 fatal shooting of Michael Robertson, a student at Santaluces High School. Quarles was 15 years old when he accused the 16-year-old  Robertson of stealing his bicycle, according to authorities. 

On Aug. 13, an unidentified woman went to sell marijuana to a buyer west of Lake Worth. The woman told investigators the man, later identified as Diaz, arrived at a gas station on the 4700 block of Military Trail, just north of Melaleuca Lane, in a newer model Toyota Camry.

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“You know Frankie, right?” Diaz allegedly asked. 

She said she knew a few people with that name. 

When he asked if she knew Frank Quarles, she said she had no idea who he was talking about. Then, she told investigators, he pulled out a gun and placed it against the side of her face. She told him to shoot if he was going to and he pistol-whipped her, according to the report.

The two physically struggled over her phone and a bag of marijuana, then he left the scene with her phone, she said.  

Frank Quarles at his sentencing hearing, Monday, March 26, 2018. (Melanie Bell / The Palm Beach Post) Photo: Melanie Bell/The Palm Beach Post

The woman did not go to police right away because she said she was in fear for her life, but investigators were alerted after she went to a hospital, according to the report. She told deputies she was diagnosed with post-concussion syndrome.

The woman told investigators she was a witness in the homicide case against Quarles and was deposed. It’s unclear what her testimony was and if she ever took the stand during the case. After checking jail call records, deputies said there were 13 calls made by Quarles to Diaz, although the report does not say when those call took place.

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Though the report does not say if Quarles and Diaz are biologically brothers, investigators said they are documented gang members. 

Diaz was on probation for a felony conviction at the time of the incident, and his ankle-monitor GPS data showed he was in the area of the alleged robbery when it happened, according to the report. It also noted that he lived just a mile away from the scene.