Is it ethical to use a recommendation letter from a deceased professor? She was a really nice professor and she wrote me a good recommendation letter that resulted in a lot of good results with applications. Recently, this professor died from brain cancer, which was a fast and shocking death for me.

Tomorrow is the deadline for a grant. What should I do? Is it professional to use letters from the deceased?
If I cared enough about a person to write a letter of recommendation, I would be pleased to think that one day after I am gone that the person could use my letter for their benefit.

You will possibly benefit from this recommendation and possibly someone else will suffer if you are selected based upon the recommendation; however, competition is not generally considered unethical.

There are no legal questions raised that I can imagine.

It seems unconventional, but not extreme.

My feelings are that it would be ethical to use the letter.