The letter, provided to The Associated Press on Tuesday by the family's lawyer, Andrew M. Stroth, asks Mayor Lori Lightfoot and police Superintendent Eddie Johnson to meet with the family, and provide dashcam and other video showing the collision and what led up to it.
The Saturday night accident that killed Verona Gunn happened when 10 to 12 police vehicles sped through an intersection as the family's car waited for them to pass, according to the letter, signed by Gunn's son, Dwight Gunn.
Gunn, the pastor of a West Side church, met with Johnson on Tuesday to demand answers for what he called the "reckless abandon" of Chicago police.
"Our mother, who we love deeply, (had) her life improperly cut short," he said.
Lightfoot, who was sworn in as mayor last week, announced a stepped-up police presence and an increase in youth programs for the Memorial Day weekend in a bid to stave off violent crime on a holiday that's seen an uptick in shootings in previous years.
The letter says an unmarked police SUV and a marked police van that were among the first responders passing through the intersection around 10 p.m. suddenly slammed into each other. It says the "unimaginable happened next" as the police vehicles then plowed into the idling family car.
The letter describes Verona Gunn as "the matriarch" of the family who worked for 30 years as a teacher. She died of her injuries around four hours later at a hospital. Two other adults in the car and a 9-year-old were also injured, it says.
"Had they taken her to a trauma hospital she may have survived the night, but because that hospital was not prepared to address her needs and they had to wait for her to get transferred to a trauma hospital, they wasted precious time," Gunn said Tuesday.
The letter thanks Lightfoot and Johnson for calling the family to express their condolences and to assure them there will be "a full and swift" investigation. The family wants to be sure that "proper training, communications and protocols are in place too so that no family has to endure what" they are suffering now, the letter says.
Asked about the letter on Tuesday, police spokesman Anthony Guglielmi forwarded a Sunday statement that had confirmed the woman had died and offering condolences to the family. That statement stops short of saying who caused the accident, saying only that officers were responding to an emergency call to assist other police when "two police vehicles collided with each other and civilian vehicles." The investigation is ongoing.