Martina Davis Correia, older sister of Troy Davis, who was executed in September for killing a police officer, died Thursday, according to media reports.

Correia, 44, had been fighting breast cancer.

She stood by her brother, who maintained his innocence in the death of off-duty Savannah police officer Mark Allen MacPhail in 1989. MacPhail was moonlighting on a security detail when he was shot three times.

After Davis' trial, a number of key witnesses recanted their testimony. Davis' case was known around the world and fueled the debate over eyewitness testimony.

Correia fought to clear her brother's name.

"She was the No. 1 messenger and was the one that really inspired people to get involved and work for him," Laura Moye, who heads Amnesty International's campaign to abolish the death penalty, told the Associated Press. "She is the person who really sparked the global campaign for Troy Davis."

Media witnesses reported that Davis, 42, addressed the MacPhail family from the gurney before his Sept. 21 execution and again proclaimed his innocence. He also asked his friends and supporters to keep searching for the truth.

“Martina Correia was a true hero and warrior for civil and human rights," NAACP President Benjamin Todd Jealous said in a statement Friday.

After Troy Davis' execution, his sister told the AP, "We're going to keep moving forward. That's what my brother would have wanted us to do, not be angry and wallow and those kinds of things."

Correia is survived by her 17-year-old son, Antone De'Juan Davis Correia; brother Lester Davis; and sisters Kimberly and Ebony Davis, the Savannah Morning News said.

This year, the Davis family also lost their mother, Virginia Davis, who died in April, the Associated Press reported.