Suicide note as a last will?

There are cases in Australia and British Columbia where a suicide note is considered as a last will even though it doesn't meet the requirements of a will because of the signatures required. The courts decided that the duress of the situation and the intent of the decedent makes the requirement of the witness's signatures not necessary.

I seem to remember a case in California and Texas where there is a will and a suicide note takes precedence over the will. Does anyone have any cases I can research? I can't find anything on Google.