Police said she was the driver of the car that lost control and struck a power pole at Main Street and Great Miami Blvd. Witnesses said the car was speeding and split in two when it struck the pole.
On Tuesday morning, Dayton police said they had questioned McGuire about a homicide and were ready to take their evidence to prosecutors for possible charges.
Detectives would not reveal which homicide case they are investigating, only that it was a murder on Main Street at the beginning of this year.
Sgt. Gary White said, "It's our belief robbery was the motive."
News Center 7 and whiotv.com reporter Jill Del Greco said research indicated that it was the murder of Robert Henning, 24, on January 15, 2009.
Henning was shot and killed in an alley off North Main Street and Indianola.
Police believe two women shot, robbed and killed Henning.
Police said they may still seek murder charges against a second suspect in the case.
Sgt. White said, "If the prosecutor's office decided that there is enough evidence and if there was a legal way to prosecutor Ms. McGuire on this homicide, then her death can still clear a portion of this homicide with the death of the offender."
White said they are still seeking charges against a second suspect in connection with the case.
"We still have another person we would like to hold responsible," said Sgt. White.