Joseph Paul Czeck, 33, of Hastings, was charged Friday with four counts of criminal vehicular homicide in connection with the crash near the Flint Hills refinery that killed 67-year-old Karen Christiansen and her 32-year-old daughter, Jena Christiansen, the Dakota County's Attorney's Office said.
Karen Christiansen, 67, was driving a Toyota Avalon north on Rich Valley Road about 4:50 p.m. when a boulder fell off a southbound truck, tumbled several times and hit her vehicle south of 125th Street, police said.
Even if an accident doesn't occur, drivers can still be pulled over and given a ticket for unsecured loads.
In a release Wednesday night, the Hennepin County Medical Examiner said the official cause of death for both was blunt force head trauma due to the crash.
"The boulder is approximately 800 pounds", Scott said.More news: Lawyer: Charges Against Stormy Daniels Dropped
Jena's boyfriend, Ryan Killian, released a statement to local news outlet WCCO saying she was "the most unbelievable person I have ever met". She was so smart and attractive.
Jena Christiansen's boyfriend Ryan Kilian posted to his Facebook page news stories about the tragedy and pictures of the killer rock, surrounded by orange pylons on the road.
"I literally have spent hours just talking to her. She had an incredible sense of humor I literally have spent hours just talking to her".
Using surveillance video, Rosemount police detectives were able to identify Czeck Services as the company that owned the commercial vehicle involved in the incident, reports CBS affiliate WCCO. Images came back of a 1999 Sterling Acterra hauling large boulders in the vicinity of the accident. According to Rosemount Police, Czeck declined to speak to authorities after his arrest. "She was with the company for over 15 years".