Earlier this week, reports surfaced saying Massa was under investigation by the House ethics committee for allegedly sexually harassing a male staffer.
The committee formally announced on Thursday that they were investigating the freshman representative. Massa already announced he would not be seeking a second term because of a cancer scare last December.
Rep. Massa released a statement taking full responsibility for things said to a staff member that made him feel "uncomfortable."
He also added that the House Ethics Committee had failed to inform him they were investigating him,and that he found out on the Internet.
"I own this reality," he said. "There is no doubt in my mind that I did in fact, use language in the privacy of my own home and in my inner office that, after 24 years in the Navy, might make a Chief Petty Officer feel uncomfortable."
He added, "In fact, there is no doubt that this Ethics issue is my fault and mine alone."
Massa, who represents the 29th Congressional District in Upstate New York, will resign from his position at 5 p.m. on Monday.