Another top Trump official has come under scrutiny for possible ethics violations while on the job.

Democratic leaders on the House Oversight and Reform Committee said Monday they’d launched a probe into “troubling” allegations against Transportation Secretary Elaine Chao. One of the longest-serving officials on Trump’s Cabinet and the wife of close Trump ally Senate Majority Leader Mitch McConnell, Chao has been accused of improperly using her office to benefit herself and a shipping company owned by her family.

In a letter to the secretary, Reps. Elijah Cummings (D-Md.) and Raja Krishnamoorthi (D-Ill.) noted that it’s illegal for federal employees to use a public office for “the private gain of friends, relatives or persons with whom the employee is affiliated in a non-governmental capacity.”

Yet, the lawmakers ― citing earlier reporting by The New York Times and Politico ― said of Chao: “Several reports indicate that you have used your official position to benefit Foremost Group, a shipping company owned by your father and sisters that is headquartered in New York and operates a fleet that transports materials to and from China.”

“These reports suggest that you used your official position …. to elevate Foremost Group’s influence and status with the Chinese government,” the letter continued, adding that China had extended “hundreds of millions of dollars in low-interest loans” to the company.

According to the Times, Chao has no formal affiliation or financial stake in Foremost Group ― but she and McConnell have reportedly received millions of dollars in gifts from Chao’s father, James. McConnell has also received at least $1 million in campaign contributions from Chao’s dad and sister, Angela, Foremost Group’s chief executive.