Do photos of dead people require a model release form to be sold?

I have a client who wants to purchase some old photos of mine. A Convalescent Home wants them for a brochure and web project. It’s a big project with 13 different web sites and brochures to market the entire Midwest.

I’ll be doing new photos of staff and clients, but they also want access to some similar photos I took 25 years ago for another Convalescent Home in Los Angeles. No doubt whatsoever that these people are dead and gone. That is not up for debate here, so please assume it is as I say.

I could not allow the photos to be used without written consent of the people if they were alive. But do I need to worry about selling these photos if the people are sure to be dead?