Publication of the Trump dossier has led to someone’s death, a lawyer for Fusion GPS, the firm that produced the dossier, said during testimony released by Sen. Dianne Feinstein (D-CA) on Tuesday.

The testimony, from a closed interview with the Senate Judiciary Committee in August 2017, revealed that when a committee investigator asked Glenn Simpson, co-founder of Fusion GPS, whether he had ever tried to assess the credibility of the dossier author’s sources, his lawyer explained that he could not answer that question.

“It’s a voluntary interview, and in addition to that he wants to be very careful to protect his sources. Somebody’s already been killed as a result of the publication of this dossier and no harm should come to anybody related to this honest work,” Simpson’s lawyer Josh Levy said.

The dossier was first published by Buzzfeed in full on January 10, 2017. It’s not publicly known who gave Buzzfeed the document. Fusion GPS, dossier author Christopher Steele, and Sen. John McCain (R-AZ) — who obtained a copy — have all denied doing so. Some media reports have speculated whether McCain associate David Kramer had given it to Buzzfeed.

Kramer had reportedly been briefed by Steele on the dossier in London, and later told congressional investigators that he knew who the sources were, but declined to name them. The House intelligence committee has subpoenaed Kramer to appear before the committee this Thursday.

The investigator responded to Levy, “I’m not asking him to identify the sources. I’m just asking what steps he took to try to verify or validate the information. If he can answer generally without identifying the sources, I’d ask him to answer.”

Levy responded, “He’s given you over nine hours of information and he’s going to decline to answer this one question.”

Feinstein made the decision to release the transcript to clear up what she said was misinformation about his interview.

The interview came before the revelation in October that the Hillary Clinton campaign and the Democratic National Committee hired Fusion GPS through their law firm, Perkins Coie, to look into then-candidate Donald Trump’s business ties in Russia. Fusion GPS then hired Steele. His research would later become known as the “Steele dossier.”