Tammy Steffens, a fitness influencer, has been sentenced to nearly five years in federal jail after pleading guilty to charges of cyberstalking and sending threats to colleagues over Instagram.

Steffens created at least 369 Instagram accounts used to harass and threaten people, one of which she told she would "slice you up into little pieces."

Authorities in Florida also allege that Steffen faked the attempted kidnapping of her 12-year-old daughter and tried to pin it on a former business partner.

Visit Business Insider's homepage for more stories.

A fitness influencer has been jailed after creating at least 369 Instagram accounts to threaten and harass several colleagues and competitors in the fitness community.

Tammy Steffen, 37, has been sentenced to nearly five years in federal prison after she pled guilty back in December to charges of cyberstalking and sending online threats, according to the Department of Justice. A federal investigation found that Steffen repeatedly called, texted, emailed, and contacted via social media at least six people over the course of two years.

She made threats to their lives and the lives of their friends and family, and tried to discredit their professional reputations, federal prosecutors say. Steffen's threats included a message telling a victim she planned to "slice you up into little pieces," and a text to another saying, "all hell is gonna rain fire down on your world like never seen before," followed by a picture of a woman holding two knives with the caption, "I'm coming," according to the police report.

However, these threats over social media and text may have been just the tip of iceberg in Steffen's alleged scheme to take revenge against competitors and former colleagues in the bodybuilding community.

Florida authorities allege Steffen organized two separate incidents in July 2018 that she tried to pin on a former business partner, according to police reports. In the first incident, Steffen reported to police that a headless doll was left on the front porch of her home, with a note inside the doll that read, "new toy for the kids."

Just five days later, Steffen reported to police that someone tried to kidnap her 12-year-old daughter, according to The Washington Post. Steffen claimed that the person grabbed her daughter's arm and tried to drag her into the woods "against her will." She also pointed authorities toward a black laptop cover found near the location of the attempted kidnapping, in which a notepad was found with Steffen's personal information on it, according to the arrest report.

When police later questioned the child, they said she asked them what would happen to her mother if she told the truth.

However, authorities say they discovered Steffen had purchased the same kind of laptop cover and notepad a few days earlier at a local Walmart. Police say they also found a witness who overheard Steffen and a friend discussing the plan to leave the headless doll on her own porch.

The Pasco County Sheriff's Office arrested Steffen in July 2018 and charged her with filing a false police report, tampering with or fabricating physical evidence, and tampering with a witness. Following her arrest, Steffen told her daughter to take the blame for the idea of fabricating the kidnapping, and told her she wouldn't get in trouble, according to police reports.

Steffen will serve her nearly five-year federal sentence after she finishes serving time related to the false kidnapping report. The Federal Bureau of Investigation didn't arrest Steffen until November on the charges of stalking and cyberbullying, the Washington Post reports.

Steffen once ran a business for training and coaching bodybuilders and bikini competitors called "Beyond Fit Bikini" out of Florida. The company hasn't posted on Instagram since January 10 (five days before Steffen was arrested), and its website is not up and running.