The attorney for TechCrunch founder Michael Arrington on Thursday denied allegations made by Arrington's former girlfriend, who accused him on social media and Internet sites of raping her, threatening to murder her and abusing her physically and emotionally.

Jenn Allen, the founder and CEO of the Rtist.com website for artists and art lovers, shocked Silicon Valley last month with accusations she made on Facebook saying Arrington had abused and threatened to murder her last year.

After the Gawker website wrote about Allen's Facebook post, Allen posted a comment on Gawker alleging that Arrington had raped her and another woman and had been taken to court "for sexual harassment and/or rape."

Thursday, on his blog, uncrunched.com, Arrington posted a letter from his Los Angeles attorney, Eric M. George, "categorically" denying Allen's allegations and demanding that she retract her statements.

Allen hasn't responded to interview requests from this newspaper. This newspaper does not normally name alleged rape victims but made an exception in this case because Allen publicly disclosed her charge.

Arrington is a powerful, pugnacious and polarizing figure who's known to give his critics no quarter. The former Wilson Sonsini attorney became one of the tech industry's most influential commentators and investors after founding TechCrunch in 2005 and selling it in 2010 for a reported $25 million.

Since Allen made her allegations, others have chimed in to slam Arrington's character on Twitter and Facebook and in blog posts.

Supporters of Arrington have also come forth. Former TechCrunch CEO Heather Harde mounted a defense of Arrington on Facebook, saying she worked long hours with him in his home, and "I would have detected patterns of abusive physical behavior if they had been present."

"During my five years at TechCrunch, there were no complaints or cases of sexual harassment or misconduct against Michael Arrington," Harde wrote. "If there had been any rumors of misconduct from staff or other third parties, I would have taken the matters seriously and investigated them. Many people, including Michael's friends and girlfriends, sought me out as a confidante for disagreements or challenges they faced with Michael, so I would have been aware of rumored bad behavior. I simply do not believe any of the allegations to be true."

On Friday, Arrington implied on his blog that more letters will be going out to those who attacked him.

"More responses are being prepared by my attorney for different parties as well," Arrington wrote.

In his letter to Allen, George said it was "factually impossible" that Arrington could have raped Allen on March 5, 2012, as she told Gawker.

On March 5, George wrote, Arrington was in Washington, and he has travel records and credit card statements confirming the trip. At 1:05 a.m. March 6, Allen was photographed at a party in San Francisco, the attorney wrote.

The photo had been posted on Allen's Facebook page but has since been deleted, George said.

Allen also told Gawker that she never saw Arrington after March 5, 2012, and only "reached out once to him."

But the attorney produced screen shots of what were described as several attempts by Allen to communicate with Arrington, including three photos she sent him the day after she says he raped her.

One of the photos included the subject line "For only you," the attorney said.

Then two days after the alleged rape, the attorney wrote, "you emailed Michael proffering extensive advice about how he ought to landscape his property."

According to the letter, 17 days "after the alleged rape, you asked Michael to invest in your start-up. ... On May 2, 2012, you asked Michael 'do you want to go to a wedding with me on May 19 in Chicago? It's also my birthday May 19.'"

In between those contacts, the attorney said, was an April 21 message to Arrington in which Allen wrote that she felt "betrayed and slighted by you, and wish I wasn't alone since you decided to be with someone else so quickly. Not sure how I'm going to teach myself how to love and trust again."

Contact Dan Nakaso at 408-271-3648. Follow him at Twitter.com/dannakaso.