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FORT LAUDERDALE (CBSMiami) – Newly obtained court documents show even more heartache and misery being quietly endured by the loved one of the massacre at Marjory Stoneman Douglas High School.

The FBI says that over a nearly three week period at the end of December and beginning of January, a California man repeatedly harassed and even threatened several of the families of the Parkland shooting victims over social media.

According to a federal criminal complaint filed in South Florida, Brandon Fleury is facing charges of harassing and threatening them using Instagram. Specifically, ”One post threatened to kidnap” the recipients of the social media posts while other messages harassed recipients by “repeatedly taunting the relatives and friends of the MSD victims, cheering the deaths of their loved ones and, among other things, asking them to cry.”

The shooting at MSD occurred last Valentine’s Day and took the lives of 17 students and staff members and left 17 others injured.

The criminal complaint makes clear that some of the messages were sent to the family of victim Jaime Guttenberg. Other posts were directed at victim Scott Beigel, a teacher at Marjory Stoneman Douglas who was shot after saving the lives of some of his students by quickly ushering them into his classroom. CBS 4 News spoke by phone with his mother, Linda Beigel Schulman.

“It makes me angry,” she said. “It really makes me angry. It doesn’t make me sad. It just makes me angry.”

Some of the posts included the following comments:

“I’m a murderer. It’s what I do, fool”

“Nikolas killed your loved ones, huh?” referring to the confessed shooter Nikolas Cruz.

Another post on Christmas Day read “I’m your abductor I’m kidnapping you fool.” The FBI wrote in the criminal complaint that the post “placed the families in fear.”

Many of the other posts are too disturbing or disgusting to mention. The FBI also writes that some of the posts came from an Instagram account that directly referenced Cruz and his actions last February 14. The feds say the suspect admitted “posting the messages in an attempt to taunt or ‘troll’ the victims and gain popularity” and “admitted to targeting family members who were ‘activists’ who had a large social media presence.” The complaint also says Fleury showed no remorse for his actions but said he didn’t plan to act on his words.

Linda Beigel Schulman believes cases this one show why law enforcement should be able to check someone’s social media history before they own a firearm.

“They need to be able to go and check his social media and check whoever it is and see that they have issues and this person should never, ever be able to own a gun,” she said.

CBS4 News spoke briefly with Fred Guttenberg. He said he’s grateful this situation was handled by the authorities and he couldn’t comment further.

Court records show that the suspect was arrested in central California and he’s due in court in Fort Lauderdale next Monday.