The NYPD is investigating online threats against the Internal Affairs Bureau detective who set off a massive ticket-fixing probe, sources tell the Daily News.

The posts, which were taken down from The NYPD Rant website on Friday, included the address and photographs of Detective Randy Katakofsky, 34.

“The department learned about the threats and had the site take them down,” one source said. “There’s now a threat-assessment type investigation underway.”

The NYPD contacted the website and told the former cop who runs it to take down the posts, sources said. Cops also went to Katakofsky’s home to make sure his safety hadn’t been compromised.

One of the posts said that Katakofsky should kill himself. There were also photos of him as a volunteer firefighter and with his softball team.

Katakofsky uncovered the summons case while investigating an officer who was suspected of having ties to a drug dealer, sources said.

A narrowly focused investigation grew into a larger probe after the cop was heard on wiretaps talking about fixing tickets.

Indictments against 17 officers are expected to be announced soon, and dozens more could face internal departmental charges or discipline, sources said.

Katakofsky has become a hated figure for some cops, who believe that ticket fixing is a professional courtesy not a crime.

More than 530 NYPD employees were caught on wiretapped phone calls during the two-year probe, sources said.

Angry union officials have said they plan to release the names of well-known New Yorkers who had tickets fixed, in order to show the “hypocrisy” of the investigation.

(Source: NY Daily News)