The findings of the OCE investigation were released late Monday by the House Ethics Committee, which said it would review the allegations. Leaders of the panel did not specify how long their review would last and stated that the decision to look at the allegations "does not itself indicate that any violation has occurred."
Bordallo, through a spokesman, denied wrongdoing and said she would cooperate with the Ethics Committee's review.
The allegations against Bordallo center on her lease of a residential property in Tamuning, Guam, to the Consul General of Japan. The arrangement produced approximately $800,000 in income since 2008, the OCE estimated.
The payments "may implicate the emoluments clause of the U.S. Constitution," investigators wrote in their report, because Bordallo "receives income from a foreign government and the emoluments clause may preclude the receipt of this profit."
The emoluments clause bars federal officials from receiving payments, gifts or compensation from foreign governments. The ban has become a topic of national discussion because of President Trump's continued financial interest in his business empire, leading to situations some ethics experts see as breaking the rule.
Bordallo's spokesman defended the arrangement in an emailed statement.
"Congresswoman Bordallo asserts that her agreement to rent her home in Tamuning to the Consul General of Japan — which was entered into in 1993, long before her election to the House of Representatives, and [from] which she has received no benefit above fair market value — does not violate federal law or House Rules," Adam Carbullido wrote.
The OCE also probed Bordallo's relationship with the Outrigger Guam Beach Resort, a property whose chain of corporate ownership purportedly includes a company controlled by her nephew, sister and brother-in-law, and several trusts benefiting other relatives.
Along with meals and amenities, Bordallo received 663 nights of free lodging at the resort starting in 2008, the OCE estimated. The office argued the stays were not permitted under House rules because they were not demonstrations of personal hospitality but came indirectly through a corporate entity.
Bordallo "continues to assert that her staying in her sister's unit in the Outrigger Hotel, which is owned completely by her sister's family, also does not violate federal law or House Rules," Carbullido stated.
Investigators also said they found evidence Bordallo used official funds to pay for her lodging at the property during at least three trips to Guam by transferring her bill to staff members staying on site. Washington-based staff are permitted to use official funds to pay for lodging in their bosses' districts, but House members are not allowed to receive reimbursements for "living expenses."
Carbullido did not address allegations about the improper use of official funds.