Did you work for a one owner company with no Human Resources Department? If that is the case something like this :

"From x date to x date I worked for xyz Company. My position was ..... The company President, Mr. pres., passed away in (date). His spouse, Mrs Pres is well aware of my employment with the company and is submitting this letter on Mr Pres behalf."

I like that a lot, Krmarchese! As the co-owner of our medical clinic, who does go through all applications of potential employees, that letter would totally work for me.

Yes, krmarchese, I worked for a one owner company. Additionally, I would like to indicate that the spouse can attest to my work ethic. They were a contractor of my employer so I worked closely with them. How could I include this information? Thanks for your help!

Since the spouse is willing to submit the letter, word it from that perspective. i.e. from date to date natebear worked for/closely with .....company. mr. .... President passed away on .... as v.p. (or whatever the spouses title is/was) i can attest to natebears work ethic and am able to recommend natebear would be an asset to any firm/company etc. Then all the spouse has to do is sign it.

Editing krmarchese's suggestion to address the last point.

"From x date to x date I worked for xyz Company. My position was ..... The company President, Mr. pres., passed away in (date). His spouse, Mrs Pres worked as a contractor to the company while I was employed there and I worked closely with her. She is submitting this letter on Mr Pres behalf."