The manager noticed the gun-a.40 Smith and Wesson-and alerted a nearby police officer who eventually arrested Donaldson.
On Wednesday, he showed up to the Ybor City McDonald's and presented a manager with the award money.
Tampa Police Chief Brian Dugan said the charging documents are still being crafted at this hour, but that police wanted to get the news out to assure the residents of Seminole Heights.
Gonzmart called the woman a hero and said he was proud to fulfill his promise.
"We said all along that no tip is too small and somebody stepped forward and gave us what we needed", Dugan said. He started there in February and worked for about three months before he was sacked for absenteeism.
CORRECTION (Nov. 29, 2017, 10:07 a.m. ET): An earlier version of this story misspelled Howell Emanuel Donaldson's name.
Including location. According to Tampa police, it was "significant" location data from a cell phone that helped link Donaldson to the crimes.
Police said they plan to be in the Seminole Heights neighborhood Tuesday night and urged people to still remain cautious and stay in pairs. The Mets would neither confirm nor deny that he was employed by them.More news: Melania Trump's Christmas 'vision' is more frightening than festive (PHOTO, VIDEO)
The man was not put in custody at the time, the chief pointed out.
The four random murders didn't appear to be robberies, leading police to believe they were the work of a serial killer.
"The person who called us, I can not thank them enough for standing up and doing the right thing", Chief Dugan said. "Today the light shines". He picked it up after the four-day waiting period and the first killing happened two days after that. "This community begins the healing process".
On Oct. 11, 32-year-old Monica Hoffa, was slain.
Benjamin Mitchell, 22, was the first to be killed in the area.
The murder of 60-year-old Ronald Felton on November 14 as he crossed the street to the food bank where he volunteered twice a week, however, spurred new leads in the case - including additional video footage of a possible suspect.
All of the October victims were either getting on or off a city bus, or were at a bus stop when they were shot, police said.