Tycoon Donald Trump was angered by a Twitter user, and has threatened to sue over being tricked into retweeting an image of serial killers Fred and Rose West.
The real estate developer shared the bogus message that the two murderers looked to him as a "big inspiration" and asked him to "RT for their memory".
Fred West was charged with a dozen murders but killed himself before the trial. His wife Rose West was convicted of 10 murders.
Some jerk fraudulently tweeted that his parents said I was a big inspiration to them + pls RT—out of kindness I retweeted. Maybe I'll sue.
— Donald J. Trump (@realDonaldTrump) September 29, 2014
When Trump realised his mistake, he later retweeted: "I guess this teaches you not to be nice or trusting."
The tycoon, who features on the US version of reality TV show The Apprentice, later deleted the message but not before it was widely shared on the social media site.
Addressing the incident, Mr Trump later tweeted: "Some jerk fraudulently tweeted that his parents said I was a big inspiration to them + pls RT-out of kindness I retweeted. Maybe I'll sue.
"I thought I was being nice to somebody re their parents. I guess this teaches you not to be nice or trusting. Sad!"
Trump has a history of threatening to sue those who cross him. In 2006, talk show host Rosie O'Donnell called him a "snake-oil salesman."
Trump responded by threatening to sue O'Donnell, saying he'd "like to take some money out of her fat-ass pockets."
The billionaire also famously locked horns with comedian Bill Maher. In January 2013, Maher appeared on Jay Leno's show and announced that he would donate $5 million to charity if Mr Trump provided evidence that he was not the "spawn of his mother having sex with orangutan."
Trump later dropped the lawsuit, filing documents in L.A. County Superior Court on 29 March 2013 to dismiss the case.