Sean Spicer freaks out over question about turning over White House notes to Bob Mueller
White House spokesman Sean Spicer in the East Room at the White House on June 5, 2017 (AFP Photo/NICHOLAS KAMM)

Sean Spicer took copious notes during his tumultuous six months as White House press secretary -- and those notebooks could be of great interest to special counsel Robert Mueller.

Former colleagues said Spicer filled "notebook after notebook" during meetings when he served as communications director for the Republican National Committee, and he continued the practice while serving on the Trump campaign and then at the White House, reported Axios.

Colleagues at the RNC used to joke that Spicer was filling the notebooks to one day write a tell-all book, but another source told Axios he used the notes to help with his work.

"Sean documented everything," the source said.

White House veterans said presidential staffers typically eschew notes, because administrations frequently fall under investigation.

Mueller has alerted the White House that he would likely interview Spicer and five other current and former Trump advisers, and one official said the president may regret his shabby treatment of his former press secretary.

"People are going to wish they'd been nicer to Sean," one White House official told Axios. "He was in a lot of meetings."

Spicer declined to comment on the report, and even threatened the reporter -- whom he's known for years -- with legal action if he continued to send unsolicited texts and emails.

"From a legal standpoint I want to be clear: Do not email or text me again," Spicer said by email. "Should you do again I will report to the appropriate authorities."