Luis Alvarez succumbed to cancer he developed years after working at Ground Zero.

Earlier this month, retired New York police detective Luis Alvarez delivered a heartbreaking plea to Congress to extend the September 11th Victim Compensation Fund, which provides financial assistance to first responders who had developed illnesses after responding to the 2001 terrorist attacks.

On Saturday, his family confirmed that the New York Police Department veteran had died at 53, having succumbed the cancer he developed years after working at Ground Zero. His legacy is cemented in his advocacy for his fellow first responders. Politicians and activists vowed on Saturday to continue the fight in his name.

Family spokesman Matt McCauley confirmed to The Washington Post that Alvarez died in the early hours of Saturday morning due to "9/11-related cancer." Alvarez had developed colorectal and liver cancer in 2016.

He is survived by his wife, Alaine Parker Alvarez, and his three children: David, Tyler and Benjamin. He is also survived by his parents Felipe and Aida Alvarez, his sister Aida Lugo, and brothers Fernando and Philip Alvarez.

"It is with peace and comfort, that the Alvarez family announce that Luis (Lou) Alvarez, our warrior, has gone home to our Good Lord in heaven today," the family said in a statement. "Please remember his words, 'Please take care of yourselves and each other.' We told him at the end that he had won this battle by the many lives he had touched by sharing his three year battle. He was at peace with that, surrounded by family."

According to The New York Times, Alvarez joined the NYPD in 1990 and began his career at a Queens precinct. He rose through the ranks, being transferred to the Narcotics Division before becoming a detective. He ultimately became a bomb squad detective, before retiring in 2010.

After he became ill, Alvarez began working with the FealGood Foundation to advocate for 9/11 victims, according to the group's founder John Feal.

"This one hurts more than usual," Feal told The Washington Post on Saturday. "This one makes my heart bleed. This one's bruised my soul, and this one is going to be hard to recover from. I miss my dear friend. Anyone who knew him should want to embrace and emulate the way he lived. He gave of himself on 9/11 and the way he lived his life until the very end. Maybe the Congress and the Senate can learn a thing from his passing."

One of Alvarez's final acts of advocacy was helping push an extension of the victim compensation fund through the House Judiciary Committee. The bill reauthorizes money for the compensation fund until 2089, ensuring decades of support for the emergency responders and their families who continue to suffer nearly 18 years later.

The existing $7.5 billion fund is in danger of running out of funds before its current 2020 expiration date. It has already paid about $5 billion to 21,000 claimants, but as of February, 19,000 unpaid claims remain unaddressed. Officials said they would have to pay reduced claims starting Feb. 1, a situation that Rupa Bhattacharyya, the special master overseeing the funds, called "horribly unfair."

Sitting beside former Daily Show host Jon Stewart at a June 11 hearing, Alvarez implored members of Congress to replenish the fund as thousands of responders and their families wait for assistance.

"I should not be here with you, but you made me come," he said. "You made me come because I will not stand by and watch as my friends with cancer from 9/11 like me are valued less than anyone else because of when they get sick, they die."

"It is my goal and it is my legacy to see that you do the right thing for all 9/11 responders," he said.

"You all said you would never forget," Alvarez said at the hearing. "Well I'm here to make sure that you don't."

Alvarez told the lawmakers that he was scheduled to receive his 69th chemotherapy treatment, but the next day he felt too disoriented to continue treatment and was placed in hospice care shortly after, according his Facebook post from June 19. "I will continue to fight until the Good Lord decides it's time."

As his death has reminded lawmakers, time is running out for many like Alvarez. Congress "cannot allow Lou Alvarez to have died in vain," bill co-sponsor Rep. Peter King, R-N.Y., wrote in a tribute on Twitter.

"His legacy lives on in all of us in this fight," tweeted Rep. Carolyn Maloney, D-N.Y., who introduced the September 11th Victim Compensation Fund renewal legislation.

Maloney told The Post earlier this month that she hopes the bill will pass the House in July.

On Tuesday, Alvarez's fellow advocates met with Senate Majority Leader Mitch McConnell, R-Ky., who told them that the Senate hoped to pass the bill by August. The meeting came after McConnell faced direct criticism from Stewart over his handling of the renewal.

During that meeting, at Alvarez's request, the activists presented McConnell with his gold detective's badge in the hopes of instilling a sense of urgency to the Senator.

"I want you to know that my time to leave this world is fast approaching," Alvarez wrote a letter to the majority leader that accompanied the badge. "My goal and legacy in this world was to see the VCF passed. You have the power to do that."

"If you pass it," the note concluded, "I will die a happy man."