Newsweek Media Group (NMG) is facing accusations of fake website traffic, amid a wider fraud investigation. Two advertising tech companies — AppNexus, which sold online ads for NMG, and SpotX, which sold video ads — have cut ties with the company, pointing specifically to fake traffic on NMG’s International Business Times websites. DoubleVerify, which offers software to verify the quality of locations where ads appear, has also warned advertisers about spurious traffic on the four IBTimes sites and Newsweek’s U.K. site.

The Wall Street Journal reports that NMG said it fired two engineers “connected with the ad issue,” although recent events still “have the potential to scare off advertisers and add to the turmoil surrounding the parent company of the storied Newsweek magazine brand.”

The Manhattan district attorney’s office is looking into “suspected bank fraud, ties with a bible college in California and alleged advertising abuses,” according to sources interviewed by WSJ. The impact of AppNexus and SpotX cutting ties isn’t clear, as NMG still “works with a range of vendors to sell ad inventory across its sites using automated software.”

DoubleVerify chief executive Wayne Gattinella and chief operating officer Matt McLaughlin report that, almost a year ago, they “started spotting patterns of invalid traffic on IBTimes.co.uk.” DoubleVerify specifies that, “code running on the sites made it appear to measurement companies that browser tabs in the background that had Newsweek or IBTimes content were visible to website visitors when they actually weren’t … [which] could be used to artificially inflate the performance of a website’s ads, leading advertisers to pay more.”

Although the assessment does not mean that the site was aware of or participated in the fake traffic, DoubleVerify “automatically prevents its advertiser customers from appearing on such sites.”

One day after NMG said it removed those codes, DoubleVerify “was still observing a similar code across some NMG sites, although it wasn’t clear how often it was being activated.” NMG is “conducting a thorough review of all of its sites to ensure they were free of potentially malicious code.” It also reports that an ad verification report conducted by Moat, between February 28 and March 6, “found the latest invalid traffic rate across its websites, at 1.52 percent … below the 3.1 percent industry average.”

The company also “plans to regularly publish its invalid-traffic numbers on its corporate site that have been verified by partners accredited by the Media Rating Council.”