When Gelvin arrived home around noon on Tuesday, Jan. 4, she was pushed down as a man grabbed her purse and fled, Alton said.
Alton said Gelvin had not been at the hospital the entire time since the robbery.
Meihls said his mother-in-law had been in "perfect health" before the robbery.
Gelvin, who was conscious after the robbery, was discovered immediately by a passer-by who helped and called 911, Alton said.
Alton said anyone who might have seen what happened or was in the area at the time may call the Washington County Sheriff's Department at 301-791-3020.
The man who robbed Gelvin was described as a light-skinned black man in his 20s. He is 5-foot-8 to 5-foot-10 with a medium build and was wearing a light-colored jacket and a cap resembling a skull cap, Alton said.
Meihls said Gelvin is survived by her daughter, Shelia "Shelly" Meihls, who lives in Fresno, Calif.
Gelvin's son, Russell Gelvin, died in April 1992 after his motorcycle hit a Mercedes head-on in Washington County, Meihls said. Russell Gelvin's girlfriend also died in that accident.
Winnie Gelvin had lived on the outskirts of Hagerstown since the death of her husband, Elvin "Dutch" Gelvin, who died about 20 years ago, Meihls said. Dutch Gelvin was a Fairchild test pilot, along with the late Richard Henson.
The couple had a wartime romance after meeting in Texas during World War II, Meihls said.
In a 1976 interview with The Morning Herald, Winnie Gelvin said she met her future husband when he was stationed at Kelly Field.
"I met him and married him six weeks later," she said. "But we've been married 35 years so it just proves that old theory about love at first sight."
The couple moved to Greensburg, north of Smithsburg, in the late 1940s, although they left several times when Dutch Gelvin got jobs elsewhere, the article states.
Meihls said the couple had farms and orchards.
Meihls said Winnie Gelvin often gave or loaned money to people.
"When you see a need, you should respond to that need," Gelvin told The Morning Herald about renting clean, comfortable apartments to young people and mothering her tenants.
"Everyone that ever met her was inspired by her," Meihls said.
Gelvin, who had two dogs, loved animals and enjoyed dancing on Saturday nights, Meihls said.
"This lady was just unbelievable," Meihls said. "Not many people talk about their mother-in-laws that way, but I can."