She died in Lillington, North Carolina.
(I assume her fictional character has no connection to the young novelist Susan Sands. There were 8 books.)
Unfortunately, I couldn't directly access her obit.
http://www.mydailyrecord.com/ee/dunndailyrecord/index.php?pSetup=dunndailyrecord&curDate=20160414&pageToLoad=showObitArticle.php§ion=Obituaries&filename=dr041416p8a.pdf.0&artId=7
Here's what I did manage to scrape out:
"Marilyn Hoagland Ezzell, 79, died March 19, 2016, at Emerald Nursing Center, Lillington. She was born March 11, 1937, to the late Paul H. Ezzell, formerly of Dunn, and Thelma H. Ezzell of New York. Ms. Ezzell was a graduate of St. Luke's School of Nursing and was a longtime resident of New York City, where she worked as a school nurse for many years. She also was author of the “Susan Sand Mystery Series,” a classic set of mystery stories for young adults that reached acclaim throughout the world, having been published in several languages. Ms. Ezzell enjoyed fine art and classic literature, particularly Arthur Conan Doyle and his Sherlock series. She also enjoyed crossword puzzles, various crafts such as knitting, crocheting, sewing and beading. Ms. Ezzell relocated to North Carolina during the latter portion of her life to take up residence at Capital Towers in Raleigh. Survivors include several cousins. A private burial will be held in Dunn at a later date."
http://www.series-books.com/susansand/susansand.html
(includes book covers and details)
http://www.goodreads.com/author/show/403580.Marilyn_Ezzell
(reader reviews)
http://daphne.blogs.com/books/2010/11/
(brief post on The Riddle of Raggedrock Ridge, #4)
https://cliqueypizza.wordpress.com/2009/03/17/a-guide-to-80s-teen-series-part-3-l-s/
(an even shorter post - scroll almost all the way down)
Lenona.