Former New York police detective and 9/11 compensation advocate dies at 53

Luis Alvarez testified before Congress earlier this month.

"He exemplified the NYPD motto, “Fidelis Ad Mortem” or “Faithful Unto Death.” Detective Lou Alvarez has lost his battle with 9/11-related cancer. An inspiration, a warrior, a friend—we will carry his sword," Shea tweeted.

In the aftermath of the World Trade Center attack, Alvarez was charged with cleaning the area and picking through waste material. He was later diagnosed with cancer, and this month he underwent his 69th round of chemotherapy.

On June 11, Alvarez joined former "Daily Show" host Jon Stewart and dozens of 9/11 first responders to demand that Congress fully fund the 9/11 Victim Compensation Fund that was set up for police, firefighters and others who worked at the World Trade Center site after the attack.

"This fund is not a ticket to paradise, it's there to provide to our families when we aren't there,” he said in his testimony.

Alvarez's family announced in a Facebook post that he is being memorialized by the NYPD.

"Please remember his words, “Please take care of yourselves and each other,” the statement said.

His family said that Alvarez would be remembered as a "warrior" who "had won this battle by the many lives he had touched by sharing his three year battle."