(CNN) Special counsel Robert Mueller asked a government agency last June to preserve documents relating to Donald Trump's transition to the presidency, according to records obtained by CNN -- an indication of how he expanded the investigation soon after his appointment.
The formal preservation request to the General Services Administration, the agency that supports presidential transitions, was sent on June 22, about a month after Mueller was named special counsel.
An email from March 2017 between the FBI and GSA -- months before Mueller was appointed -- suggests FBI investigators' interests at that time were narrower. Then the FBI asked GSA to consult with lawmakers before disposing of other transition documents.
The more expansive request came when an agent in the FBI's counterintelligence division emailed the deputy general counsel at GSA to preserve documents, electronics and communications from the Trump transition team, according to documents CNN obtained through a Freedom of Information Act request.
"As a follow up to our request, we thought it best to send GSA an official preservation letter. Your staff has been extraordinarily responsive and we appreciate their patience with our (my) questions," the agent wrote, according to the email obtained by CNN. GSA redacted the name of the FBI agent who sent the email.
Mueller was named special counsel in May after the firing of FBI Director James Comey by the President. Mueller was given a broad mandate to continue the investigation started by the FBI into any links, coordination or both between the Russian government and individuals associated with the Trump campaign and "any matters that arose or may arise directly from the investigation."
The FBI request to the GSA appears to confirm a fear that the President's friends warned him about last spring. They worried that a special counsel, which comes with broad authority to investigate any matters deemed relevant, could lead to an expansive investigation beyond what the FBI had in its initial inquiry.
In the March email, James Baker, the FBI's then-general counsel, emailed Lenny Loewentritt, the GSA deputy general counsel, following up on a conversation the previous week between a GSA attorney and Peter Strzok, the FBI counterintelligence supervisor who was later removed from the Mueller team after text messages critical of Trump surfaced.
In the email obtained by CNN, Baker noted the FBI asked GSA to preserve all stored communications, records and electronic media associated with an individual or entity with a redacted identity. He went on to say he understood that GSA may have a cell phone, laptop and emails "used by or associated" with someone whose identity was redacted and asked GSA to preserve the devices until further notice.
Baker also asked GSA to consult with Senate and House intelligence committees before disposing of devices and information associated with other members of the transition team. The email was forwarded to others within GSA, noting, "We may get additional inquiries or direction from the FBI."
GSA ultimately complied, handing over thousands of documents.
Mueller's interest in the transition emails became the source of a controversy in December when the Trump transition team wrote to members of Congress accusing the special counsel of obtaining unauthorized access to tens of thousands of transition emails, including some they claim are protected by attorney-client privilege. The transition said the emails, which were on a government server, were private.
The transition said it reached an agreement on June 15 with GSA that the transition "owned and controlled" the emails and data and any requests for documents would be routed to the transition. That decision, the transition said, was communicated to the special counsel's office the next day, nearly one week before Mueller's team sent its email requesting GSA preserve transition emails.
The special counsel made two separate requests for emails, laptops and cell phones in August covering 13 individuals associated with the transition.
Peter Carr, a spokesman for Mueller, told CNN at the time, "When we have obtained emails in the course of our ongoing criminal investigation, we have secured either the account owner's consent or appropriate criminal process." He declined to comment on the emails CNN obtained.