Anissa Weier is seeking release from a mental hospital after luring a 12-year-old friend into the woods for a tribute killing to the internet meme character Slender Man.

Now 19 years old, Ms Weier appeared in a Wisconsin court as prosecutors asked for a delay to file written arguments on whether she should be released.

Ms Weier was sentenced to 25 years in the Winnebago Mental Health Institute after a jury found she was not criminally responsible for her part in the 2014 stabbing that gained international notoriety and inspired the HBO documentary Beware the Slenderman.

After luring classmate Payton Leutner into a Waukesha park after a birthday sleepover, Ms Weier cheered on as friend Morgan Geyser stabbed Ms Leutner 19 times.

All three sixth-graders were 12-years-old.

Both plead guilty, telling detectives that they would become Slender Man's servants if they killed their friend. They feared the Slender Man would harm them or their families if they didn't kill someone.

“Many people do not believe Slender Man is real,” one of the girls said, according to the criminal complaint. “[We] wanted to prove the sceptics wrong.”

Speaking in court, Me Weier told Waukesha County Circuit Judge Michael Bohren that she has spoken with her attornies and is was satisfied with their representation.

Ms Weier petitioned to be released in November, with a letter she wrote was presented to the court on Wednesday, according to the Milwaukee Journal Sentinel. Multiple psychologists and psychiatrists evaluated Ms Weier in recent month and also filed their reports to the court, which have been sealed.

Deputy district attorney Ted Szczupakiewicz said he has been in contact with the victim, who barely survived the stabbing, on how the state is proceeding.

Judge Bohren gave prosecutors until 26 March to submit arguments, and the defence until 9 April to respond. The next hearing is scheduled for 11 June.

"I understand the nature of the case, obviously, but also the nature of the procedural aspects of the matter with regard to the reports and how to present," Mr Bohren said, according to the Journal Sentinel.

"Arguments oftentimes in very serious matters and complicated, sophisticated matters can oftentimes be best presented by written arguments that can be amplified through oral arguments as well."

If released, Ms Weier would be tracked until she is 37-years old by case managers from the Department of Health Services.

Ms Geyser is serving a maximum 40-year sentence at a mental health facility.