To my knowledge there is no circumstantial evidence in Kathleen's case which would point to foul play.
There has been no word as to if it was thought Kathleen was alive or dead at the time the fire started or what may have been learned from the toxicology report regarding CO2 levels or other drugs that may have been in her system if she decided to possibly overdose herself.
The description given of Kathleen's remains was "The Lake County coroner told FOX6 News the fire was so intense, parts of the remains were cremated, in essence, and could not be positively identified using regular methods." and "Everything looks like ash,"
Read the complete article here:
Burned beyond recognition: Illinois coroner works to ID remains found in Milwaukee teacher’s car
JMO