There are many cases where new evidence has led to overturning convictions of those on death row. Now a panel of fire investigators commissioned by the Innocence Project finds:

Faulty evidence masquerading as science sent two men to death row for arson in Texas and led to the execution of one of them. -- New York Times

The report is critical of the lack of training for arson investigators and says:

There is no crime other than homicide by arson for which a person can be sent to death row based on the unsupported opinion of someone who received all of his training “on the job.”

The report is a disturbing read at best. Throughout are examples of places where experts are testifying that they know arson when they see it. On that basis a man was executed and another lost 17 years of his life to death row.