A mental examination has been ordered to determine if a 21-year-old visitor from Overland Park, Kansas, who allegedly stabbed the captain of a Kona charter boat is fit to stand trial.

Kona District Judge Kimberly Tsuchiya on Monday granted the motion by Deputy Public Defender Victoria Andrade-McKeehan to determine the fitness of Avery J. Nissen without objection by Deputy Prosecutor Madeline Walsh.

Nissen is charged with attempted second-degree murder, plus first- and second-degree assault, for allegedly attacking 62-year-old Stanley Lurbiecki — the captain of the catamaran “No Wiki” — with a filet knife during a snorkeling tour Thursday off the Kona coast.

Nissen’s 55-year-old mother, Kristina Nissen, his 23-year-old sister, Sydney Nissen, and Nissen chartered the boat for a snorkeling tour. Both Lurbiecki and a 42-year-old deckhand identified as Iaian Cook reportedly told police they were informed by Kristina Nissen that her son is autistic.

Lurbiecki allegedly told police that Avery Nissen “was acting strangely and appeared to be anxious” during the cruise.

When the boat reached the snorkel destination, Nissen reportedly panicked while in the water and re-boarded the boat. As the boat was returning to Honokohau Harbor, Nissen allegedly told Lurbiecki that he wanted to go to Kona and pointed in the direction of Kailua Pier.

According to the captain, Nissen walked around the boat, opening and closing cabinets and pacing around while everyone else was eating lunch on the lower deck.

Nissen then stabbed Lurbiecki in his lower right back, and he attempted to wrest the knife from Nissen, suffering wounds to both his hands, according to the documents, which do not contain a motive for the attack.

Nissen’s mother reportedly came to the upper deck and helped the captain remove the knife from her son’s grasp. Lurbiecki reportedly said that during the struggle, the knife “eventually dropped to the deck floor,” and Nissen jumped into the ocean, attempting to flee.

Lurbiecki allegedly told police that he called “man overboard.” The captain reportedly said the boat was backed up to Nissen’s position, but he didn’t know how Nissen was brought back aboard.

Lurbiecki used a towel to apply pressure to his wounds and was assisted by Nissen’s sister, according to documents.

Upon reaching the Honokohau Harbor, Lurbiecki was met by medics and police and was taken by ambulance to Kona Community Hospital.

According to a medical disclosure form completed by emergency room physician Dr. Stephen Petrou, Lurbiecki suffered stab wounds to his lower right back and abdomen, both sides of his head and both hands. According to Petrou, there was substantial risk of death from an abdominal hemorrhage suffered by Lurbiecki.

Tsuchiya ordered Nissen to return to court at 1 p.m. June 17 and maintained his bail at $1.57 million.

If convicted of the attempted murder charge, Nissen would be subject to a mandatory sentence of life imprisonment with the possibility of parole. First-degree assault is a Class B felony that carries a maximum prison term of 10 years upon conviction, and second-degree assault is a Class C felony with a maximum sentence of five years behind bars.

Email John Burnett at john.burnett@hawaiitribune-herald.com.