Army Major Gen. Ronald Lewis was fired last year as the senior military assistant to Carter after the Defense Department began a probe into allegations of misconduct.
In a report by the Pentagon Inspector General, investigators said Lewis misused his government charge card for personal expenses, made false statements about his use of the card, drank in excess in public and had improper interactions with female subordinates.
"I expect the highest possible standards of conduct from the men and women in this department particularly from those serving in the most senior positions. There is no exception," Carter said in a written statement.
In his role at the time, Lewis had power to control the flow of people and issues into Carter's office, as well as handling the defense chief's schedule.
The investigation revealed an April 2015 incident when Lewis, who was accompanying Carter on official travel, visited a strip club in Seoul, South Korea, where he charged $1,121.25 on his government credit card and left an 81% tip, according to the report.
The "Candy Bar" club was in a part of Seoul known as "Hooker Hill" where many establishments have been declared off limits to military personnel because of their ties to illicit activities such as prostitution.
According to the report, Lewis subsequently denied using the card at the establishment and disputed the charges to the bank.
Lewis, a married father and highly decorated officer who graduated West Point, acknowledged in a statement that he "made some of the mistakes" outlined in the report, but he "strongly" disputed many of the report's findings, although he did not specify which ones.
"From the onset, this process was unfairly influenced by statements made and actions taken at the highest levels of the Department of Defense," Lewis said in the statement issued by his lawyer.
On a trip with Carter to Rome in October 2015, the report said Lewis used his government credit card to cover a $1,755.98 tab at another adult establishment known as the "Cica Cica Boom" club, which advertised "sexy show" and "lap dance" on a sign outside, after the charge on his personal debit card was declined.
Lewis was accompanied by a "female foreign national" employee of the strip club back to his hotel to retrieve his government credit card from a subordinate who was holding it for him. The subordinate, who was staying on the same floor as Carter, "felt like something very wrong was about to happen, but I wasn't in a place to tell him," the report said.
The investigation also found that on trips to Malaysia and Hawaii, Lewis "engaged in physical contact with female subordinates observed by witnesses where the contact was not incidental or innocuous."
It cites an incident in which Lewis "drank to the point of not being sober" while in Hawaii and noted his attempted kiss of a female enlisted service member required her to "reject and physically block his inappropriate and unwanted advance."
The Inspector General has referred its report to the Army. Disciplinary action could range from a letter of reprimand that would end Lewis's future promotion opportunities or assignments, effectively ending his military career,to a decrease in retirement pay from the military upon his separation from the services.