Four decades after she slipped away from Texas authorities, Rivera was returned to Houston this week and will make her first court appearance Friday. The ailing 76-year-old is charged with murder by omission in the October 1970 death of her husband, Cruz Rivera.
"It was a shock to me when I heard about it," said Lorraine Robertson, who knew Rivera for more than 25 years and lived in the same Georgia apartment building. "I was like, that's not Mary. She wouldn't do nothing like that."
Court records allege that Rivera was accused of killing her husband by "throwing hot grease on him and by throwing other substances and liquids." The documents don't indicate a motive, and authorities said police were never called to the couple's Houston home on allegations of domestic violence.
One of her sons, Mark Rivera, declined comment when reached at his home in South Carolina. Court records do not list an attorney for his mother, whose health required that she be driven and not flown back to Houston. She is being held without bond.
Rivera had been a fugitive since she posted a $10,000 bond in 1970 following her indictment. Authorities said she fled with her three children, including twin sons, and eventually made her way to Lake Park, Ga., a town near the Florida border.
An investigator with the Harris County District Attorney's Office in Texas worked on the cold case for several months, first tracking down Rivera's sons and eventually finding her Georgia address, said office spokeswoman Donna Hawkins.
Hawkins wouldn't comment on a possible motive for the alleged slaying.
Officials with Georgia's Lowndes County Sheriff's Office arrested Rivera after being contacted by Houston police.
Robertson said investigators first spoke to Rivera at her apartment about six weeks ago, asking her questions about who she was and her husband.
"They asked her how (her husband) treated her. She said they got along, raised their kids," Robertson said. Rivera had indicated that her husband had slapped her once but "that was it," Robertson said.
Investigators returned a month later and asked her similar questions. Robertson said Rivera had not previously talked about her husband and told investigators that she moved to Georgia after he died.
When investigators returned a third time, on Oct. 11, they arrested Rivera.
"Me and another neighbor walked her out. I could feel her whole body trembling," Robertson said. "We put her in the car. She cried. We all cried with her."
Robertson questioned why Rivera was being arrested after so many years and noted her frail health, including heart, back and breathing problems.
Hawkins, declining to address the health problems, said Rivera needs to face justice.
"The defendant was charged with committing a rather brutal murder of her husband. Although she was able to elude authorities for over 40 years, she ultimately must face judgment in a court of law for the murder of her husband," Hawkins said.