The fact that the aide, Cheryl Mills, was taking part in such a high level task for the Clinton foundation while also working as chief of staff for the secretary of state raises new questions about the blurred lines that have dogged the Clintons in recent years.
Upon entering office as secretary of state, Hillary Clinton and the Clinton Foundation agreed to a set of rules to ensure any activities by the foundation would not "create conflicts or the appearance of conflicts for Senator Clinton as Secretary of State."
On June 19, 2012, Mills, then the chief of staff for Clinton at the State Department, boarded a New York City-bound Amtrak train in Washington's Union station.
The next morning, at the offices of a New York based executive search firm, Mills would interview two high-level business executives. Her mission was to help the Clinton Foundation find a new leader, a source told CNN.
According to Mills' attorney, her work for the Clinton Foundation while she was employed at the State Department was strictly voluntary. She received no pay and no government funds were used to finance the short trip.
Clinton's presidential campaign re-iterated that Mills was working as a volunteer on the trip.
"Cheryl volunteered her personal time to a charitable organization, as she has to other charities," said campaign spokesman Brian Fallon. "Cheryl paid for her travel to New York City personally, and it was crystal clear to all involved that this had nothing to do with her official duties. The idea that this poses a conflict of interest is absurd."
The Senate Judiciary Committee, chaired by Republican Chuck Grassley of Iowa, has tried to get answers about Mills' New York trip as well. Grassley sent Secretary of State John Kerry a letter in January asking the purpose of Mills' trip. The State Department did not officially respond to the letter.
"Congress has a rightful right to ask for any information that it wants to from the executive branch of government to keep track of them," said Scott Amey, an attorney for the Project on Government Oversight. "And the government should be turning that information over, when you have a breakdown in that system, we have a breakdown in our democracy."
There is no doubt of the connections between Clinton Foundation staffers and State Department staffers.
E-mails obtained through the Freedom of Information Act and released by the conservative watchdog group Judicial Watch this week raise new questions about the intermingling of Clinton Foundation business, its donors and employees under Hillary Clinton's control as a public servant. They suggest Foundation officials had no problem trying to curry favor for jobs by emailing top Clinton aides like Mills and Huma Abedin, who is now a senior adviser to Clinton's presidential campaign.
Mills' trip from Washington, D.C., to New York by a top Clinton aide in 2012 seems to raise the same potential issues.
The top-level executives Mills would interview for the big job at the Clinton Foundation worked at Pfizer and WalMart -- companies that have been huge donors to Foundation, and have worked with the Clinton Global Initiative.
CNN has asked the US State Department if Mills had, or needed permission for the trip, or if the State Department was even aware Mills was involved with the Clinton Foundation while a top aide of Secretary Clinton. A State Department spokesperson responded by stating:
"Federal employees are permitted to engage in outside personal activities, within the scope of the federal ethics rules. All federal employees are subject to federal ethics laws and regulations, including rules pertaining to conflicts of interest."
It's easy to understand why Mills was trusted with helping find the next director of the Clinton Foundation. Her relationships with the Clintons goes back decades.
As Bill Clinton's Deputy White House counsel, she defended the then president during impeachment proceedings.
In 2008, when Hillary Clinton was running for president, Mills was her senior legal campaign adviser.
And when Hillary Clinton became Secretary of State, Mills left the board of the Clinton Foundation and became Hillary Clinton's chief of staff.
Now, she is once again on the board of the Clinton Foundation while running her own development business focusing on African business.