A Florida jury convicted a California man of cyberstalking and harassing the friends and family of Parkland shooting victims.

Last year's mass shooting at the Marjory Stoneman Douglas High School killed 17 students and staff members.

Brandon Michael Fleury, 21, was accused of sending more 300 messages to the survivors and family and friends of victims, threatening them with kidnapping.

Fleury reportedly created 13 separate Instagram accounts to conduct the harassment. One of those handles was named after the Parkland shooter, the other, after the serial killer Ted Bundy.

Fleury told authorities he was trolling and that he picked the victims because he viewed them as "activists."

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A 21-year-old California man was found guilty this week of cyberstalking and harassing the families and friends of teens who died during the Marjory Stoneman Douglas High School shooting in Parkland, Florida, last year.

Brandon Michael Fleury, 21, reportedly created 13 separate Instagram accounts to send over 300 harassing messages where he threatened the friends and family with violence and kidnapping.

In one of the messages seen by NBC News, Fleury claimed that "with the power of my AR-15, you all die." This appears to have been in reference to the Parkland shooter, who himself used an AR-15 to kill 17 students, faculty, and staff.

Fleury claimed the threats were a macabre attempt at trolling.

'Your grief is my joy.'

According to court documents seen by NBC News, Fleury began his verbal attack last December. The Instagram handles used reportedly used the names of the Parkland shooter and the infamous serial killer Ted Bundy. Fleury used these accounts to repeatedly "taunt" the families and friends of Parkland victims who he considered to be "activists," according to court documents viewed by NBC News.

"Your grief is my joy," Fleur reportedly wrote in one message viewed by the Sun-Sentinel. "I killed your loved ones, hahaha."

Attendees pass a wooden cross as they arrive at a candlelight vigil for the victims of the shooting at Marjory Stoneman Douglas High School, Thursday, Feb. 15, 2018, in Parkland, Fla. Associated Press/Wilfredo Lee

Florida officials traced the messages of the multiple accounts back to a single IP Address in Santa Ana, where Fleury was living with his father and his brother at the time. Since Fleury's victims were located across the country the 21-year-old was ultimately charged with one count of transmitting a kidnapping threat, in addition to three counts of cyberstalking.

The jury's decision came after a six-day trial in Fort Lauderdale. An assistant public defender attempted to argue that Fleury has a form of autism that prevented him from understanding the fear his 301 messages evoked, the Sun-Sentinel reported.

"He [Fleury] did not understand that these people were afraid," Fleury's federal public defender Daryl Wilcox said according to the Sun-Sentinel. Fleury's father reportedly took the stand and echoed the autism defense. That argument fell on deaf ears with Florida prosecutors arguing that Fleury was well aware of the hurt and pain he caused by that he, "just doesn't feel it."

Fleury is scheduled for sentencing on December 2. He faces up to 20 years in federal prison.