CBS News has reviewed documents that show the anonymous whistleblower reached out to the intelligence community watchdog on October 8 to clarify the nature of his or her contact with Democratic majority staff of the House Intelligence Committee before the complaint was filed.

The whistleblower acknowledged reaching out to the committee, but claimed that nothing substantial was discussed and that the staff member directed them to go through official channels, according to the "Memorandum of Investigative Activity," provided to House and Senate Intelligence Committee leadership by intelligence community inspector general (ICIG) Michael Atkinson. The form is dated October 18 and documents the October 8 outreach by the whistleblower.

Republicans have seized on the contact with Democratic committee staff to question the credibility of the whistleblower, while Democrats have downplayed the significance.

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According to the document, the whistleblower reported to the ICIG investigator that the committee staffer advised: "'Do it right, hire a lawyer, and contact the ICIG.' So that is what the COMPLAINANT did. At the time, COMPLAINANT did not even know what the ICIG was."

The whistleblower felt that "[b]ased on getting guidance on a procedural question, and that no substance of the actual disclosure was discussed, COMPLAINANT did not feel, based on the way the form question was worded, that it was necessary to check that box."

"That box" refers to the whistleblower disclosure form, which requires a detailed accounting of who is aware of the complaint. The box for "Congress or congressional committee(s)" was left blank by the whistleblower.

The whistleblower complaint that set the impeachment inquiry of President Trump into motion was filed in August and became public in September.

On October 2, the New York Times first reported that House Intelligence Committee Chairman Adam Schiff had "learned about the outlines" of the whistleblower's concerns before the complaint was submitted to the ICIG, citing a spokesman, as well as current and former American officials.

Patrick Boland, spokesman for Schiff, said in a statement at the time: "Consistent with the Committee's longstanding procedures, Committee staff appropriately advised the whistleblower to contact an Inspector General and to seek legal counsel. At no point did the Committee review or receive the complaint in advance."

The whistleblower, who spoke by telephone with the ICIG's office on October 8, addressed "news reports and questions regarding how the Office of the Inspector General of the Intelligence Community (ICIG) Hotline forms were completed."

Separately, on the issue of potential congressional testimony, the whistleblower expressed a preference for written questions from the Senate or House Intelligence Committees. According to the records, the whistleblower "does not wish to testify in person" and "does not believe there was any point for him/her to come forward given all that has come out in the news. He/she is not interested in being part of a political show."

The whistleblower, according to the ICIG, believed that "much of the information provided by him/her at the time of the urgent concern disclosure has now been overcome by more detailed information coming out in the press, or recent text message releases, which are beyond his/her original knowledge. Some of the dates of information being disclosed in the news do not match up with Complainant's urgent concern disclosure."

That "text" reference likely refers to messages submitted to Congress that illustrated attempts to broker a White House meeting between Ukrainian president Volodymyr Zelensky and Mr. Trump, as well as issues surrounding military aid.

The October 8 call is not the Office of the Inspector General's only contact with the whistleblower - the ICIG, according to the letter, "has remained in contact with the Whistleblower for other reasons," offering to help ensure the individual's "personal safety and offering to facilitate any interviews...with the Congressional oversight committees."

Sources familiar with Atkinson's closed-door deposition in October tell CBS News that Atkinson said he did not investigate the contact between Schiff's committee and the whistleblower because he first learned about it from the media. The transcript of Atkinson's deposition has not been released.