A 19-year-old has admitted being one of two teenage girls who relentlessly abused a 15-year-old St. Francis girl in a beating that was captured on video and seen on Facebook more than 500,000 times.

The video was posted on Facebook by the victim’s mother within days of the June ambush in dark woods near the Ponds Golf Course in St. Francis.

Cassandra T. Borden, of nearby Cedar, pleaded guilty Monday in Anoka County District Court to fifth-degree assault, a misdemeanor. Dismissed was a charge of misdemeanor fourth-degree property damage, in connection with the victim’s broken cellphone during the ambush. Borden and the prosecution agreed to no jail time and restitution to her victim of $669. Formal sentencing is scheduled for Nov. 14.

Borden struck Sydney DeTenancour, who was 15 at the time of the beating on June 17, nearly 50 times after saying during a profanity-laced tirade that Borden caught the victim with “my man,” according to the charges.

The attackers, also accused DeTenancour of “snitching” on Borden’s boyfriend, who was cited for drunken driving. They snipped off a chunk of DeTenancour’s long hair.

Alexis S. Nelson, 19, of Zimmerman, was also charged with fifth-degree assault and has a pretrial hearing set for Dec. 19. Nelson is not accused of hitting DeTenancour but did snip off several inches of the victim’s hair as DeTenancour was on the ground being kicked and punched, the video showed and the criminal complaint alleged.

DeTenancour came away with bruises, red marks and scratches “all over her body and face, and a large section of her hair had been cut off,” the charging documents alleged.

The teen’s beating has inspired a modest antibullying campaign led by her family and friends. T-shirts and bracelets have been made in DeTenancour’s honor, and a “Syd’s Angels” motorcycle ride was held in September with the mission of raising awareness about bullying among young people.

The video also shows a third female straddling and punching a prone DeTenancour; she identifies herself as the sister of the man caught drinking and driving. That third attacker is a juvenile, possibly explaining why charges against her have not been made public.