Ron Wyden (D) of Oregon, the incoming chair of the powerful Senate finance committee, is seeking extensive records from Children’s Health Defense (CHD), the non-profit anti-vaccine group Kennedy has used as a vehicle to fuel his political rise, including all documents related to a 2019 trip Kennedy took to Samoa.

The trip, which Kennedy made as the chair and chief legal counsel of CHD, became one of the most criticized events in his career before he entered government. Critics, including Samoan officials, have said Kennedy’s presence emboldened anti-vaccine activists in Samoa, worsening a vaccination crisis. Kennedy has denied the allegations, saying he never gave any public statement about vaccines or discouraged Samoans from getting vaccinated.

But letters obtained by the Guardian and the Associated Press through an open records lawsuit brought by the Reporters Committee for Freedom of the Press contradicted that testimony. In one he wrote to the Samoan prime minister in January 2019 before the trip, Kennedy explicitly said he wanted to study the measles, mumps and rubella (MMR) vaccine in the Pacific island nation. In it, he used the words “vaccine” or “vaccination” eight times.

The prime minister responded a month later, saying Samoa could benefit from CHD’s assessment of MMR vaccines and inviting him to come.