Top correction officers union members so feared former boss Norman Seabrook’s wrath they dared not challenge his investment of $20 million in a risky hedge fund, an ex-union official told The Post.

“He was supposed to bring that before the executive board for a vote, but he circumvented that and made the transaction on his own and didn’t involve us,” said William Valentin, who was the board’s corresponding secretary.

Seabrook’s investment of $20 million of pension money and union cash in little-known hedge fund Platinum Partners in 2014 allegedly earned him a kickback of $60,000 in cash and a promise of more, Manhattan US Attorney Preet Bharara charged last week.

Seabrook violated union bylaws by circumventing the 15-member board, Valentin said.

Seabrook also gave $250,000 in union money to former Comptroller John Liu’s 2013 mayoral campaign “and none of us knew anything about it,’ Valentin said.