( CNN) The FBI this week detained and questioned Ted Malloch — who says he was an informal Trump campaign adviser in 2016 who was rumored last year to be a candidate for US ambassador to the European Union — as part of special counseling Robert Mueller's investigation, Malloch said.

“The questions get more detailed about my involvement in the Trump campaign( which was informal and unpaid ); whom I communicated with; whom I knew and how well — they had a long list of names, ” Malloch said. “They seemed to then focus more attention on Roger Stone( whom I have met a grand total of three times and with groups of people ); Jerome Corsi, a journalist who edited a memoir I had written some years ago; and about WikiLeaks, which I knew nothing.”

He said was asked specifically if he had visited the Ecuadorian Embassy in London, where WikiLeaks founder Julian Assange has been holed up for nearly six years. He had not, he said.