Does benzodiazepine use cause sudden cardiac death?

No: If a person suffers sudden cardiac death while taking these, even to a moderate excess, i would look for a different cause. I'm a pathologist and this question comes up frequently. If you have lost someone you love, i hope you are able to find an explanation, as well as strength and comfort.

Respiratory failure: Benzodiazepines are central nervous system depressants ('downers') so when mixed with alcohol or taken in excess they cause respiratory failure (stop breathing). Several famous people may have died this way: marilyn monroe, elvis and even heath ledger had 3 benzodiazepines in his system. However, respiratory failure leads to cardiac failure.