There was speculation the women attempted to kill herself by driving off an overpass in Edmonton an hour before the children were found. She is in custody and being evaluated.
Here is an excellent resource on female offenders that I found online.
Allan Schoenborn was found not criminally responsible for murdering his 3 children - 10yr old Kaitlynne, 8yr-old Max and 5yr old Cordon - in April 2008 in Merritt BC during a visit after his common-law wife had relocated from Vancouver with the family. He was found 9 days after the incident - having clearly failed at taking his own life. Here was some key points in the judge's decision:
B.C. Supreme Court Justice Robert Powers, who heard the three-month trial in Kamloops without a jury, found that the killings were deliberate and planned by Schoenborn, but that he was not sane at the time.
"I find on balance of probabilities he was suffering from a disease of the mind," Powers told the court Monday.
Powers rejected the Crown's assertion that Schoenborn killed his children as revenge against their mother.
"I find it unlikely [he] would have killed his children out of anger given the close and caring relationship he had with his children," said Powers.
"Mr. Schoenborn, if anything, was overprotective. The irony is that the real danger to the children was Mr. Schoenborn himself and none of the dangers that he imagined in his mind."
But Powers said Schoenborn's imaginary fears can't justify his crime.
"Any reasonable or rational person would know that was wrong," he said. "However, due to his psychosis at the time he was not able to make that decision."
Schoenborn spoke out twice during Powers's reading of his judgment, saying only, "bullshit."
References: PDF1, PDF2, PDF3.
Update - 2013 Sept "Child killer Allyson McConnell found dead" Sydney Morning Herald