I am looking for the date of death of an old friend of the family. 
His name is Ken Deddens or perhaps Kenneth Deddens.  He is buried in
Jefferson Barracks National Cemetery in St. Louis, Mo.  He was a
veteran of the US Navy.  That's all the information I have.  If you
could find out when he died, I would greatly appreciate it.  Thanks
you for your time.

Here is the information that I obtained from the Social Security Death Index:

Name 
KENNETH E DEDDENS

Birth
09 Sep 1919 

Death
03 Jul 2000 (V) 

Last Residence 
63119 (Saint Louis, MO) 

My search strategy involved a visit to the Social Security Death Index
(SSDI), where I entered the last name DEDDENS and the first name
KENNETH.

Social Security Death Index (SSDI)
http://ssdi.genealogy.rootsweb.com/

This obituary was printed in the St. Louis Post Dispatch on July 6, 2000: 

"DEDDENS, KENNETH E., Mon., July 3, 2000; beloved husband of Marilyn
Deddens (nee Carpenter); dear father of Tom (Ann) and Daniel (Gina)
Deddens; dear grandfather of Julia, Timothy, Heather and Erik; dear
brother of Ethel (Eugene) Koeller and Allen (Elise) Deddens and the
late Raymond Deddens; our dear brother-in-law, uncle, cousin and
friend.

Visitation at KUTIS AFFTON Chapel, 10151 Gravois, Thurs., July 6, 4-8
p.m.; then taken to Webster Groves Presbyterian Church (45 W.
Lockwood, 63119)"

St. Louis Post Dispatch Archives
http://nl.newsbank.com/nl-search/we/Archives?p_product=DO&p_theme=do&p_action=search&p_maxdocs=200&s_dispstring=allfields(deddens%20kenneth)%20AND%20date(2000)&p_field_date-0=YMD_date&p_params_date-0=date:B,E&p_text_date-0=2000&p_field_advanced-0=&p_text_advanced-0=("deddens%20kenneth")&p_perpage=10&p_sort=YMD_date:D&xcal_useweights=no

I hope this is precisely what you need. If anything is unclear or
incomplete, or if a link doesn't work for you, please request
clarification; I'll gladly offer further assistance before you rate my
answer.

Best regards,
pinkfreud

That's exactly what I was looking for. Thanks for your help.

Thank you very much for the five stars and the nice tip!

~pinkfreud