WASHINGTON — Brian Sicknick’s family wants to uncover every detail about the Jan. 6 insurrection by pro-Trump rioters, when the Capitol Police officer collapsed and later died.

They can’t understand why lawmakers do not.

Sicknick was one of the on-duty officers badly outnumbered by the mob who stormed the building, smashing windows and breaking through barriers.

He was sprayed with a chemical, collapsed, and later had a stroke and died.

His family was on Capitol Hill Thursday meeting with lawmakers opposed to the measure that would form an independent commission to investigate the riot.

His mother, Gladys Sicknick, sent a letter earlier this week to Republican senators asking for a meeting and urging them to vote for the commission.

“My son has been gone for over four months, and I want answers, that’s all,” she said in a brief interview Wednesday with the Washington Post.