The House Ethics Committee cited “insufficient evidence” and shuttered an investigation Friday into whether six lawmakers misused official travel funds, even as some Members acknowledged keeping the money or spending it on items such as souvenirs for their offices or families.

The committee’s report also highlighted continuing tensions with the Office of Congressional Ethics, which recommended the probes to the House panel, over investigative methods and interpretations of the chamber’s rules.

According to the 805-page report released Friday by the ethics committee, the OCE reviewed whether each of the Members had improperly kept excess per diem funds issued for official Congressional travel, known as a CODEL, between 2008 and 2010. The lawmakers denied violating rules.

The funds were intended for meals or other approved expenses. In its evaluation, the OCE determined that six lawmakers retained excess funds ranging from $428 to $2,811, based on estimates of each lawmaker’s travel expenses.

But the House Ethics Committee rejected the OCE’s estimates, including its use of Members’ official itineraries to estimate meal costs and even lawmakers’ admissions that they may have used the funds for nonessential items, like gifts.

“The Committee concludes that there is insufficient evidence to determine with any degree of certainty that any one of the Members were provided an amount of per diem that was not necessary for their respective trips,” the panel stated in its report.

“While OCE also relies on statements to the press and to OCE by the Members that they have purchased meals or gifts for foreign officials, staff or aircrew members who supported the trip, a use of per diem that the Committee would agree would not be appropriate, there is no evidence that per diem was actually used for such expenses, or that the amount of per diem if used was not de minimis,” the report said.

The OCE had reviewed trips taken by Reps. Robert Aderholt (R-Ala.), G.K. Butterfield (D-N.C.), Eliot Engel (D-N.Y.), Alcee Hastings (D-Fla.), Solomon Ortiz (D-Texas) and Joe Wilson (R-S.C.).

Members are not required to maintain receipts for their per diem expenses, and some of the six lawmakers said they often commingled their own funds with their government-issued local currency or used the funds to repay expenses charged to their personal credit cards or bank accounts.

Because individual receipts were not available, OCE investigators instead relied on official trip itineraries to estimate costs for each Member by determining how many official or “leisure” meals were scheduled.

According to summaries of its interviews with the six lawmakers, OCE investigators also sought to determine whether a Member’s meals most often fell into one of three categories: official events provided at no charge, meals paid for by the military and later billed to the Member, and meals paid for by the Member.

But the ethics committee rejected the OCE’s method, citing arguments offered by Hastings that many of those meals are receptions with limited food or where Members do not eat. The committee also said Members may not adhere to official travel itineraries filed with the House and asserted there is no proof that Hastings or the other lawmakers even attended the events tallied in the OCE reports.

“Representative Hastings frequently did not attend the scheduled meals because of other responsibilities and would usually dine elsewhere using his per diem,” the ethics committee report stated.

“Representative Hastings would generally make an appearance at the scheduled receptions and then leave to have dinner elsewhere,” it also stated, citing a Hastings aide and an unnamed military liaison. “They stated that it was also not unusual for Representative Hastings to have commitments other than those listed on the itineraries or to not eat at the scheduled events.”

Each of the lawmakers denied wrongdoing in interviews with the OCE or subsequent communications to the ethics committee, although some acknowledged retaining funds or using funds on spouse travel, which is prohibited, or souvenirs for staff or family.

In a July letter to the OCE, Butterfield contended that the House rules on foreign travel do not require Members to keep expense records or to refund excess funds.

“Alternatively, I request that you find that any misunderstanding of the rule should not be attributable to the member because of the failure of the Department of State or House Leadership to inform members of this responsibility,” he wrote.

In a letter to the OCE, Ortiz said he believed he used “all, or almost all” of his per diem funds “during my official travel.”

“Your investigation and the Speaker Nancy Pelosi’s recent May 13 announcement [instructing Members to return excess funds] have now put me and other members on notice that we have an obligation under current House Rules to return unspent per diem,” Ortiz wrote. “Now that this requirement has been clearly established, you can rest assured that I will keep accurate records to make sure House Rules are respected on any future travel.”

Both Hastings and Engel, however, told investigators that per diem funds rarely covered the costs of travel, and each have paid travel-related funds from their own pockets during official trips.

“When asked if he ever had per diem left over following a CODEL … [Engel] explained that he believed there were times that he had no per diem remaining and had to spend his personal money and there were times he had a little left, but it was negligible. Negligible meant less than $100 per trip,” the OCE report stated

According to the OCE report, Engel’s post-travel disclosures, which detail the use of per diem, were prepare and signed by a staffer. “Of the seven forms such as this that had his signature, only one of them was actually signed by him,” the report stated.

Engel, who told OCE investigators he uses per diem funds to purchase a souvenir for the aide who arranges the CODEL travel, said the forms were accurate.

In his interview with OCE staff, Aderholt also said he uses some of his per diem funds for souvenirs “such as T-shirts for his son” and “postcards, a doll, wallet and leather goods.”

The OCE report stated that Aderholt told investigators: “He believed that it was appropriate when he purchased souvenirs with per diem because he would use his personal money to pay for his lodging or meal if he did not have enough per diem due to the souvenir expense.”

During the OCE’s review, Aderholt repaid a bill for meal expenses that he received in connection with a 2008 trip. According to the report, Aderholt issued a check for $120 to the U.S. Treasury for meals the military provided to him during the trip, after he could not locate a previous check for the amount.

The OCE investigation was sparked in part by an early 2010 Wall Street Journal article reporting that Members routinely pocketed excess per diem on foreign trips. Each of the six lawmakers was quoted in the report, copies of which were included in each of OCE’s reports.