The New York Democrat resigned last month after allegations surfaced that he sexually harassed male members of his staff.
The committee cannot investigate former members. Rather, the panel will look into what others knew about Massa's conduct, and what they did with any information they received.
Beginning in March 2009 and over the next several months, several male staffers complained that the 50-year-old married lawmaker had touched them in a sexual manner, came up with reasons to have staffers travel alone with him on overnight trips, and expressed a desire to have sex with the men in the office, the newspaper reported.
Senior staff -- even one of whom who heard an inappropriate remark -- tried to handle the problem "internally," the documents indicate. But reports of Massa's inappropriate behavior continued, leaving junior workers feeling "helpless," the Washington Post said.
In one instance, a staffer said he alerted Massa's chief of staff, Joe Racalto, that Massa had allegedly tried to fondle a young colleague in a hotel room during the 2008 campaign. Two sources said that Racalto told staffers he himself had been a victim of Massa's advances, the Post reports.
It took about a year and threats of public humiliation before the matter was referred to the House leadership committee.
Massa resigned amid the growing scandal but gave various reasons for stepping down, even saying he was pushed out by Democratic lawmakers because he had voted against the health care reform bill. Democratic leaders called the allegation "absurd."
Massa continued to deny he had any inappropriate interactions with his employees, but he told Fox News conservative commentator Glenn Beck that he had "groped" staffers in what he said was a non-sexual manner. He also admitted having what he called "tickle fights" with staffers but denied the move was sexual in nature.
Some staffers said the Massa episode reveals congressional staff's lack of faith in their workplace protections.
"Both the Chief of Staff and the Deputy Chief of Staff attempted to rein in the Congressman, but their efforts were ineffectual and by the fall of 2009, Congressman Massa's behavior spiraled out of control," Debra Katz, attorney for one staffer who alleges he was harassed by Massa and has initiated a complaint against him, said in a statement to the Washington Post. "This left my client and other gay men in the office even more vulnerable to Representative Massa's predatory behavior."