“Slender Man” stabber Morgan Geyser could be sent back to a mental institution after authorities asked a court to revoke her conditional release after she escaped from a Wisconsin group home to be with her trans friend last week.

On Wednesday, a Waukesha County Circuit Court judge agreed to seal the petition filed by the Department of Corrections late on Tuesday seeking to revoke the 23-year-old’s conditional release.

Geyser did not fight her extradition to Wisconsin during a Chicago court appearance Tuesday.

Wisconsin authorities now have 30 days to pick her up, according to a statement sent to The Post.

If her conditional release is revoked, she could be sent back to the Winnebago mental institution where she spent most of the past eight years.

She could also face fresh charges in connection with her escape.

Geyser, who at age 12 in 2014 almost killed her classmate in the name of internet horror villain Slender Man, was approved for release from a state mental institution to live in a group home earlier this year by a Waukesha County judge.

On Saturday evening, she cut off her ankle tag with a pair of scissors and fled the Madison, Wisconsin, group home with her transgender pal, Chad Mecca, 43, according to authorities.

The pair were arrested on Sunday night in Posen, Illinois, some 170 miles away from the home.

Geyser and her preteen accomplice, Anissa Weier, avoided jail time despite stabbing classmate Payton Leutner 19 times after luring her into a wooded area during a sleepover in Waukesha.

After the girls got Leutner to lie down under the guise of playing hide and seek, Geyser stabbed Leutner in the torso, arms and legs while Weier egged her on.

One of Leutner’s doctors said the girl was a “human hair” away from death as one of the wounds missed a major artery by a millimeter.

Leutner was able to crawl out of the woods and was taken to a hospital after being discovered by a passing cyclist.

Geyser and Weier were arrested several hours later by the side of a freeway.

They told police they were walking toward where they believed Slender Man lived in a mansion.

The pair were charged with attempted murder and tried as adults.

In 2017, both were found guilty by reason of mental disease or defect and were committed to the Winnebago Mental Health Institute — Geyser for 40 years and Weier for 25.

Weier was released in 2021 on the condition that she wear an ankle tag and move in with her father.

Geyser was granted conditional release after a hearing in January of this year, before finally moving into a group home in late October after months of delays.

Wisconsin health department officials opposed Geyser’s release, saying she was caught reading a book about murder and black market organ harvesting, and communicating with a collector of murder memorabilia.

Leutner’s mother also expressed concern that the group home Geyser was originally going to be sent to was just eight miles from where her daughter lives.

Following Geyser’s escape, Leutner’s family put out a statement saying she was safe.

“Payton Leutner and her family [are] aware of the most recent situation regarding Morgan Geyser. Payton and her family are safe and are working closely with local law enforcement to ensure their continued safety,” read the statement, as reported by the Milwaukee Journal Sentinel.

“The family would like to thank all of the law enforcement entities involved in the efforts to apprehend Morgan. The Leutner family also wish to thank the outpouring of support from family, friends and well-wishers who have contacted them during this difficult time,” the statement concluded.

Leutner said she still sleeps with a pair of broken scissors under her pillow “just in case” her attackers return, during an ABC News interview in 2019, but added that she wasn’t afraid of Geyser being released.

“If she ever tried to come by me, she would go right back where she was,” Leutner said.