RedactedNarrative: On 08/20/21 at about 10:10 a.m. I, CPO, was informed by Sgt. that an individual was missing on Fox Lake.  According to Sgt, the person was being pulled on a tube behind a pontoon boat when the tube overturned and the individual had not been located.  I proceeded to the Lake County Marine Unit to prepare a patrol boat.  While loading the boat, I was called by Acting Capt..  AC told me he was also on his way and to wait for him.  At about 11:00 a.m., AC arrived and we proceeded to the staging area for the search.
  
  At about 11:15 a.m., AC and I made contact with parties involved.  Operator 1 was operating the 23 foot pontoon boat involved in the incident. Two children were also on board the pontoon (later identified as the 2 year-old son and 4 year-old daughter of Operator 1). The children were wearing required personal flotation devices.  The required orange flag for skiing/tubing was also displayed at the stern of the watercraft.  Illinois registration numbers were not displayed on the watercraft, although I did note a 2019 rental boat sticker on the side of the boat.  When I asked if anyone could tell me what had happened, Operator replied, "We were just getting going when the tube flipped over and victim fell in the water.  We got the kids out, but then we couldn''t see him.  We drove towards another boat to get help, but when we got back, we couldnt'' see him anymore."  Operator then said she had driven around, "for a few minutes" looking for victim before calling 911.  When I asked who was operating the boat when victim was on the tube, Operator said, "I was."  AC asked if anyone knew which direction they had been heading when the accident happened.  Operator 2 replied, "I really don''t know.  It was just water all around us.  We were in the middle of nowhere."  AC asked Operator 2 if he felt he could operate the boat back to where it had been rented.  He said he thought he could. At no time did anyone in the party suggest any mechanical problems with the watercraft had caused or contributed to the accident.  As the search was ongoing, AC asked Operator 2 to take the boat back to the resort where it had been rented (on Petite Lake).  I gathered phone numbers and told them I would contact them as soon as we had more information.  AC and I then went to join the search for victim.
  
  AC and I, along with representatives of other rescue squads, assisted the Fox Lake Fire Department with a side-scan sonar search until about 8 p.m.. We then turned our patrol boat over to CPO, who continued the search until around midnight on August 20, 2021.
  
  On 08/21/21, at about 7:30 a.m., CPO and I responded to the staging area at Fam''s on the Chain to continue the search for victim.  CPO and I helped maintain a search perimeter for the sonar boats, which were being coordinated from shore.  At about noon on 08/21/21, the search was suspended for the day due to increased boat traffic and the inablility to maintain a perimeter for the sonar boats.  
  
  CPO and I returned to the staging area and met with parties involved.  I then asked Operator some questions from the Illinois Boat Accident Report form.  She indicated she was operating at the time of the accident.  She also reported she had no, formal boating training and had never attended a boating safety course.  She said she was just beginning to increase speed while victim and his children were on the tube when the tube flipped over.  Operator 2, and children all reported that they were able to get the children back onboard the boat but that their efforts to rescue victim we...