Boulder, Colo., police investigating the death of 6-year-old beauty princess JonBenet Ramsey have asked for copies of autopsy and police reports on an apparently routine traffic accident in Downers Grove Township that led to Ramsey's half-sister's death.

Ramsey's half-sister, Elizabeth Pasch Ramsey, and her boyfriend, Matthew Derrington, died in the Jan. 8, 1992, accident on I-55 near County Line Road after Derrington's car crashed into a truck.

Boulder police would not say why the accident reports were requested about a month ago.

"We're just following up on any and all leads in the Ramsey investigation," said Leslie Aaholm, a spokeswoman for Boulder police.

Aaholm would not say whether investigators had been to Chicago or whether they planned to interview people here.

Elizabeth Ramsey was the daughter of JonBenet's father, John Bennett, and his former wife, Lucinda Pasch. Her death certificate said she died of multiple injuries resulting from a car accident.

At the time of the accident, Elizabeth Ramsey was a 22-year-old flight attendant for Delta Airlines. Her home address was Marietta, Ga.

According to a state police report, Elizabeth Ramsey was a passenger in the car, which went out of control on rain-slicked I-55 at County Line Road and collided with a truck.

A spokesman for the Cook County medical examiner's office said the autopsy report was mailed or faxed to Boulder police a month ago.

Since 6-year-old JonBenet's body was discovered in the basement of her family's Boulder home on Dec. 26, authorities have released few details about the case. But on Thursday, Boulder prosecutors said John and Patricia Ramsey have not been eliminated as suspects.