The deal between virtual reality headset maker Oculus VR and social media giant Facebook is under a different form of scrutiny this week, as video game company ZeniMax Media claims that a former employee stole its intellectual property and gave it to Oculus VR. ZeniMax believes that it has the rights to Oculus Rift and seeks to either end the deal or gain compensation.

One current Oculus VR employee, John Carmack, used to work for ZeniMax, designing video games for the company. ZeniMax says that when Carmack left ZeniMax, he took the company's intellectual property with him to Oculus VR. In the past few weeks, ZeniMax's lawyers have sent letters to Carmack, as well as Facebook and Oculus VR contesting Facebook's rights to buy the VR gaming startup.

ZeniMax says that it has evidence that Carmack stole its ideas to help create the Oculus Rift VR headset. Carmack allegedly contacted Oculus VR founder Palmer Luckey in 2012 when he was still working for ZeniMax. At the time, Luckey was working on a virtual reality headset at the University of Southern California. Carmack supposedly asked Luckey to send him a prototype, which Carmack then turned into a rough VR gaming headset.

ZeniMax claims that Carmack then showed off this modified VR headset at the ZeniMax booth during a gaming conference in Las Vegas that June. In one video shot at the conference, Carmack is seen claiming that he created the software that turned the headset from a dream prototype into a workable device.

Around the same time, Luckey founded Oculus VR. Although Carmack only recently joined Oculus in the summer of 2013, ZeniMax still believes that the prototype he made while under its employ later became the Oculus Rift headset. To make matters worse, five other ZeniMax employees joined Oculus in early 2014.

ZeniMax first sought compensation from Oculus VR and Carmack back in August 2012. Almost two years later, no deal has been reached.

Of course, Oculus doesn't see it that way. From Oculus' point of view, ZeniMax's claims have nothing to do with facts and everything to do with wanting money.

"It's unfortunate, but when there's this type of transaction, people come out of the woodwork with ridiculous and absurd claims," an Oculus spokesperson told the Wall Street Journal. "We intend to vigorously defend Oculus and its investors to the fullest extent."

Now that Facebook has offered up the big bucks to buy Oculus VR, ZeniMax is fighting back. In a statement, ZeniMax said it "sent formal notice of its legal rights," and that "ZeniMax believes it is necessary to address these matters now and will take the necessary action to protect its interests."

On April 18, ZeniMax contacted Oculus' lawyers and Facebook's general counsel, Colin Stretch.

"It was only through the concerted efforts of Mr. Carmack, using technology developed over many years at, and owned by, ZeniMax, that Mr. Luckey was able to transform his garage-based pipe dream into a working reality," the letter read.

At this point, it is unclear if Facebook knew about the dispute between Oculus VR and ZeniMax before it offered $2 billion for the company in late March.