The Republican primary for a state Assembly seat on Staten Island's South Shore last year was especially nasty. A Facebook page about one of the candidates drew threats against her life, triggering a police investigation. It was not known who was running the account — until now. Our Amanda Farinacci has the details in this exclusive report.

As Republican Janine Materna ran for Assembly last year, a Facebook page emerged that looked like something her campaign might have created.

But several posts on it were out of step with Materna's conservative Staten Island district.

Like this one: "Mayor Bill de Blasio is right. We need a homeless shelter in Annadale."

Another post declared," Black Lives Matter" -- and showed a photo of Materna with former Obama Attorney General Eric Holder. It appeared to upset at least one voter, who posted, "Sorry hun you just lost my vote."

At the time, Materna claimed she was the victim of a dirty trick. "I believe that my opponent has really used a lot of smear tactics on social media against me, which I think is very distasteful," she said.

Materna's opponent in the Republican primary, Ron Castorina, denied any involvement.

Materna narrlowly lost that race, and it remained a mystery who was behind the Facebook page – until now.

Materials obtained by NY1 show local lawyer Richard Luthmann was the page’s administrator — and apparently communicated about what it should contain with Materna’s opponent.

"I have no comment," Luthmann told NY1. "And I'm gonna have to, I'm compelled to assert the attorney-client privilege."

NY1 obtained screen shots of Facebook conversations between Luthmann and Castorina in which the creation of such a site was discussed.

"Janine Materna filed a committee," Castorina begins.

Luthmann replies, "Time for a fake Janine Materna site..."

"Is there a picture of her with Hillary?" Luthmann asks.

"I’m looking for one," Castorina replies.

Eventually, a doctored photo of Clinton supposedly standing with Materna appeared on the page, with the statement. "On September 13" — the date of the GOP primary — "we will make HERstory."

In another Facebook conversation, Luthmann sent Castorina that photo of Materna and Holder, and an image linking Materna and Mayor de Blasio, adding:

"In a news feed near you very soon!"

"Good," Castorina replied. "She's a vicious animal."

"I would be disappointed if it turns out that that's what happened," said State Senator Diane Savino, when asked this week about NY1's findings.

"And I would hope that any elected official, or any would-be elected official, would think twice before they would engage in something like that type of activity."

The Materna page did contain a disclaimer, one that could easily be overlooked by Facebook users: It said, "This is an UNOFFICIAL FAN PAGE…" It included a link to Materna's official page.

Facebook records obtained by NY1 also show Luthmann is the administrator for a Councilwoman Debi Rose page. She's locked in a tight democratic primary against Kamillah Hanks.

One post talks about a fundraiser hosted by a real estate developer. It says "his campaign contributions will help me to turn this St. George property into a heroin/methadone den."

Luthman also was the administrator of a page created under the name of Michael McMahon, during his hotly contested race for Staten Island District Attorney.

Another – dubbed "Lyin' Nicole Malliotakis" — targets this year's Republican mayoral candidate.

"Politics has always been a blood sport," Savino said. "But it's going to, taken it to different levels now because of the prevalence of social media."

Materna calls these misleading pages a form of bullying, saying she’s disappointed and disgusted people engage in it. She declined an on camera interview request.