Marine veteran Magdalena Jablonska was killed as she sat beside her fiancé when a high-powered pontoon struck their smaller boat.
MCHENRY, Ill. — A newly filed lawsuit alleges a high-powered pontoon traveling about 75 mph in a no-wake zone struck and rode over a smaller boat on the Fox River, killing 48-year-old U.S. Marine veteran Magdalena Jablonska as she sat beside her fiancé.
The civil complaint adds new allegations about the July 25 collision south of the McHenry Dam, where prosecutors say Richard M. Stevenson, 45, of Lisle, was operating a 31-foot South Bay pontoon before it struck a 20-foot Crownline from behind. Stevenson also faces criminal charges of reckless homicide and aggravated driving under the influence causing death. He has not been convicted, and the allegations in both the criminal and civil cases remain subject to court proceedings.
The lawsuit alleges Stevenson was traveling about 75 mph as he entered the no-wake area and approached the Crownline carrying Jablonska and her fiancé. Attorneys for the family say the smaller boat was moving slowly when the larger pontoon hit it from behind with enough force to ride completely over it. Prosecutors have separately said witnesses described Stevenson’s boat as traveling at an extremely high rate of speed, with some estimates placing its speed near 80 mph.
The civil complaint says Jablonska was sitting only inches from her fiancé when the collision occurred. The impact caused fatal injuries to Jablonska and also injured her fiancé, according to the lawsuit. Authorities and court records have described her injuries as catastrophic. The McHenry County coroner reported preliminary findings of blunt-force injuries to her head and body. The more graphic details contained in court filings are not necessary to understand the circumstances of her death.
McHenry County prosecutors said Illinois Conservation Police officers responded at about 2:30 p.m. and found the severely damaged Crownline along with Stevenson’s pontoon, which had run aground nearby. Investigators determined that the larger vessel had struck the rear of the Crownline before riding over it. Stevenson was later located in trees off the shoreline near where his boat came to rest, prosecutors said. Two other occupants of his boat left before law enforcement arrived.
Stevenson was taken to Northwestern Medicine McHenry Hospital after the crash. Prosecutors said a blood test showed a blood alcohol concentration of approximately 0.200. A criminal complaint cited a toxicology result of 0.236, according to local reporting. Both figures are well above Illinois’ 0.08 threshold for operating a vessel while under the influence. Witnesses also told investigators that Stevenson had been consuming alcohol during the day and had been operating his boat at high speeds before the crash, prosecutors said.
The state’s attorney’s office said evidence presented at Stevenson’s detention hearing showed he had previously been charged with driving under the influence on three occasions, reckless driving on three occasions and had four prior misdemeanor speeding offenses. A judge granted prosecutors’ request to keep him detained before trial. Those previous charges were cited by prosecutors during the detention proceeding and do not by themselves establish responsibility for the July 25 crash.
The wrongful-death case seeks to hold Stevenson and potentially other parties financially responsible for Jablonska’s death and her fiancé’s injuries. Attorneys representing the family have said their investigation extends beyond the conduct of the boat operator and will examine the events leading to the collision. The legal team has said it intends to use boating-safety specialists, accident reconstruction experts and marine engineering consultants as the civil case develops.
Jablonska, of Des Plaines, had immigrated from Poland and later served six years in the U.S. Marine Corps, according to her family and attorneys. Relatives remembered her as generous, devoted to her family and deeply interested in helping animals. Her family said she frequently supported animal shelters and helped people in need. A visitation was scheduled for Aug. 9 in Park Ridge.
The criminal case also moved forward this week. A McHenry County judge ordered multiple law-enforcement agencies to preserve video, audio recordings, DUI testing materials and other evidence connected to the investigation. Stevenson remained in the McHenry County Jail and was scheduled for a preliminary hearing Aug. 21. The civil lawsuit and criminal prosecution are separate proceedings, and Stevenson is presumed innocent of the criminal charges unless proven guilty beyond a reasonable doubt.
Author note: Last updated August 7, 2026.