A British lawmaker has challenged Netflix to provide evidence for the claim that Baby Reindeer‘s real-life Martha has a stalking conviction.

John Nicolson, a Scottish National Party MP who sits on UK Parliament’s influential Culture, Media and Sport Committee, said Netflix had a duty to back up claims made in Richard Gadd’s “true story” hit series after Martha was identified as Fiona Harvey.

In a letter seen by Deadline, Nicolson asked Benjamin King, Netflix’s senior UK director of public policy, to provide evidence of Harvey’s criminal record after he told the committee that Baby Reindeer was a “true story of the horrific abuse” suffered by Gadd “at the hands of a convicted stalker.”

Nicolson wrote: “Journalists have thus far been unable to find a record of the conviction to which you referred. Can you provide me with the evidence for this serious claim which you made to me at the Select Committee?” The full letter is below.

Nicolson stopped short of alleging that King had made a misleading statement. Knowingly making untruthful statements during select committee hearings can result in being held in contempt of Parliament in the UK.

The alleged stalking conviction is at the heart of questions facing Netflix. In Baby Reindeer, Martha (played by Jessica Gunning) is portrayed as pleading guilty to stalking and being sentenced to prison. Since being identified, Harvey has denied the allegations and a lawyer acting on her behalf said there was no evidence that she has a criminal record for stalking.

Chris Daw KC, a barrister working with Harvey to build a lawsuit, told Deadline: “Portraying someone as a convicted criminal who has done time in prison, when that is not true, is a pretty clearcut case of defamation, as it is bound to cause serious harm to that person’s reputation.”

Daw is assembling a team of lawyers in the UK and U.S. to pursue Netflix, producer Clerkenwell Films, and Baby Reindeer creator Gadd, but has yet to be formally instructed by Harvey.

Netflix is not responding to inquiries relating to Baby Reindeer. During last week’s committee hearing, King said Netflix took “every reasonable precaution” to protect identities. Senior sources in the UK television industry have scoffed at this notion. A former high-ranking BBC executive, who has experience in compliance procedures on factual dramas, said Netflix should have changed details including Martha’s profession and her nationality.

Baby Reindeer is in many ways a British success story. Made by Clerkenwell, it exploded on Netflix, amassing nearly 65M views since debuting on April 11. It was Netflix’s top English-language series for three consecutive weeks.

Nicolson’s full letter to Netflix: