Donald Trump repeats a lot of lies about Hillary Clinton’s use of a personal email account he hears on cable news, but an attack ad released on Thursday seems to be based entirely on his own imagination.

The ad, which is based on innuendo and leaks from pro-Trump sources inside the F.B.I., asserts without evidence that Clinton is under investigation because “her emails were found on pervert Anthony Weiner’s laptop.”

In fact, at the time the ad was produced, there was no such claim even in the flood of leaks from the F.B.I. to reporters about their review of email found on the laptop belonging to Weiner’s estranged wife, Huma Abedin, who was one of Clinton’s closest aides during her tenure as secretary of state.

The primary source for the accusation appears to be Trump’s own sexist assumption, first articulated last year, that Abedin must have shared classified information with Weiner, since, he said, any woman who is “in love with” her husband would certainly do so.

“Are there any women in this room who are in love with their husbands who wouldn’t be telling them everything?” Trump asked supporters at an event in Massachusetts. When one woman said she did love her husband but would not break an oath to keep classified information secret, Trump replied dismissively, “No, you will.”

Several hours after the new attack ad was posted online, CBS News reported that the F.B.I. found emails “sent to or from an email address connected to the private Clinton sever,” on Weiner’s laptop that agents had “not previously reviewed.”

However, that does not mean that any of Clinton’s own emails were found on the laptop or that there is any secret information there. As Abedin told the F.B.I. in April, as a longtime aide to Clinton, she had an email account of her own on Clinton’s private server — Huma@clintonemail.com — “which she used for matters related to Clinton’s personal affairs, and to communicate with Clinton’s personal staff and friends.”

According to the F.B.I. transcript of her testimony, Abedin also said that, because she found it difficult to print email she received on her State Department email account, “she routinely forwarded emails from her state.gov account to either her clintonemail.com or her yahoo.com account so she could print them.”

Since, Abedin explained to the F.B.I., Clinton herself did not use a computer at all, she would often ask aides to print out emails or attachments for her to read. Indeed, a search of the 33,572 emails Clinton turned over to the State Department that are now online reveals that 4,279 of them included the shorthand phrase “pls print.”

Often, as in the case of a Nov. 30, 2010 email from Clinton to Abedin, which Abedin then forwarded from her state.gov account to her clintonemail.com account, the messages simply contained articles someone had advised Clinton to read. (On that day, it was the full text of a New Yorker article critical of WikiLeaks that was making the rounds in the State Department, two days after diplomatic cables leaked by Chelsea Manning were first published.)

In other words, the CBS report could mean nothing more than that the review of Abedin’s email on her husband’s laptop had turned up messages from her own account connected to the server in Clinton’s home, and might not include any government secrets.

On the campaign trail, Trump has repeatedly distorted reports sourced to unnamed officials in the F.B.I. that there are 650,000 emails on the laptop, claiming that some or all of those emails belonged to Clinton. “Last night, CBS News just confirmed that the 650,000 emails include brand new emails not previously seen by authorities,” Trump told supporters in New Hampshire on Friday.

“She said she gave them all in, right?” he added. “Hillary Clinton lied to Congress under oath when she said she turned over all of her work-related emails.”

At another rally in Ohio on Friday, Trump claimed, again without evidence, that the emails on Weiner’s laptop (which might well be almost all his own) included 30,000 personal emails Clinton had deleted as unrelated to her work at the State Department, and that some of them were “beyond classified.”

While Trump seems perfectly capable of making things like this up from whole cloth, a report by Wayne Barrett for the Daily Beast suggests that there could be an alternative explanation for how this attack ad was produced before any information on what was on Weiner’s laptop even leaked to the media.

As Barrett explains, it seems likely that pro-Trump F.B.I. agents have been providing information on the email investigation directly to Trump’s campaign via Rudy Giuliani, a former federal prosecutor with close ties to the bureau’s New York office.

In an interview with Fox News on Friday, Giuliani admitted that anti-Clinton agents inside the bureau have been in touch with him as he has been campaigning for Trump.

Abedin, meanwhile, has been off the campaign trail as the F.B.I. reviews her email. As she was greeted by Anna Wintour at a fundraiser for Clinton in Washington on Thursday night, video showed that Trump supporters heckled her by referring to the debunked conspiracy theory that she is a secret agent of the Muslim Brotherhood.