Cause of death changed: How often does this happen?

Factual Questions
1

A local woman served thirteen years in jail strangling her daughter, but new results say that the girl died as a result of cocaine use.

http://www.wkbw.com/news/local/15613772.html

This made me wonder, about the question in the title. I’d assume it’d have to be rare just because once a case is closed, that’s usually it. Are there any statistics on this?

2

Dr. Charles Smith, the former chief pediatric pathologist at the Hospital for Sick Children in Toronto, Ontario was recently found to have been making erroneous conclusions of homicide in his autopsies. 44 autopsies were reviewed by the Office of the Chief Coroner and at least 20 of them were found to be questionable.

3

http://www.chron.com/content/chronicle/special/03/crimelab/index.html

Massive problems in the Houston Crime Lab have led to innocent people being released and very serious looks taken at some convictions.

Houston Crime Lab Scandal: After DNA Proves Innocence - TalkLeft: The Politics Of Crime (link I found, I’m not familiar with the website.)

But basically, if you live in the Houston/Harris County area–most people are rethinking some guilty findings.

4

Thanks. That’s pretty scary.