Murphy said he witnessed Grimm get into at least one heated altercation during their race. He also pointed to footage of Grimm arguing with an elderly man from his 2010 campaign and an incident where the congressman's assistant, Marc Alvarez, allegedly cursed at a group of skateboarders at an event for a city council candidate.
"He's a big dude," Murphy said of Alvarez, "and he's got a big bald head, and he essentially stands in as Michael's bodyguard wherever he goes. Some kids at a local skatepark started heckling ... and he went over there and he just ripped into them."
TPM called a phone number believed to belong to Alvarez on Wednesday. A short time later, a man called back from the same number and identified himself as Alvarez.
"Don't call my house again," he said before hanging up.
A few minutes later, TPM called back to verify that he was indeed the person who worked for Grimm. TPM assured him that a reporter would not be calling again.
"You obviously just did," the man said. "I just told you not to and you did. This is my house. You don't call my house. This is the second time. Call me again and I'm going to put in a harassment call. OK?"
Murphy also cited events from Grimm's past including a 1999 incident where the future congressman allegedly threatened patrons at a nightclub and a 2012 congressional breakfast where Grimm reportedly "picked up and wielded a butter knife" to express displeasure with Rep. Steve Israel (D-NY).
"This is a total pattern of behavior with this guy," said Murphy. "He's an absolute thug, he's like the 'Mob Wives' congressman."
Despite describing Grimm as having a history of alarming behavior, Murphy said he largely avoided the congressman's wrath during their race.
"I'm bigger than he is, so I don't think he's going to threaten me physically," Murphy said. "He's not going to try that with me."
But Murphy said one of his donors experienced the congressman's rage.
"He went ballistic on the guy for giving me money," said Murphy, who previously served as an aide to former New York City Public Advocate Bill de Blasio, who is now the city's mayor.
Murphy also pointed to the speech Grimm gave after his win in 2012 as evidence of his temperament.
"He lashed out even on election night saying that I was a disgrace to my family. You know, you realize that this is a guy who can't be gracious," Murphy said.
In those remarks, Grimm described Murphy as "despicable."
"I have no respect for him as a man, a person or anything," said Grimm. "He has disgraced himself and his family."
For his part, Murphy seemed convinced Tuesday's threats wont be Grimm's last outburst.
"He has a switch and that guy's going to snap. He really is," Murphy said.
This post has been updated to include comments from Alvarez.
Photo by Jon Reznick.