The prosecution said Monday that it plans to summon the eldest daughter of Korean Air chairman Cho Yang-ho on Wednesday as part of its ongoing investigation into the escalating “nut rage” row.

Sources said charges are unavoidable against Cho Hyun-ah, also known as Heather Cho, formerly a top executive at the family-run flag carrier, amid new claims she subjected flight attendants to abusive language and violence. 

The 40-year-old forced a Korean Air flight to return to the gate to deplane the cabin manager on Dec. 5 at New York’s JFK airport after expressing her anger about the way some nuts were served in the first class cabin.

During the process, Cho ordered the senior attendant Park Chang-jin along with a stewardess to kneel in front of her and pushed him into the cockpit door, according to Park.

After the incident was posted on the online bulletin board of the airline’s union, a civic group filed a complaint against her for violating aviation law and interrupting business, followed by immediate raids on the airline’s Seoul and Incheon offices.

In the face of an intense public backlash and an investigation launched by state authorities, Cho stepped down from all her posts at the airline and its affiliates on Friday ― the same day her father offered a deep bow of apology to the public.

“I sincerely apologize for the trouble that my daughter’s foolish behavior caused. As the chairman of Korean Air and her father, I ask for your forgiveness,” he said in a news conference held at the company’s Seoul headquarters. “Please, blame me. It is all my fault.”

The prosecution is expected to decide on the final charges against Cho as soon as the analysis of the plane’s black box is completed.

They were also considering summoning other company officials to determine whether they had tried to conciliate the flight attendants and passengers to make them favorable witnesses.

The Ministry of Land, Infrastructure and Transport plans to announce the initial results of its own probe into the incident Tuesday morning even though it failed to question the cabin manager, who disappeared after a TV interview, for a second time.

The 41-year-old Park, who was ordered to get off the plane, had earlier said he did not suffer any violence at the Land Ministry’s earlier questioning but overturned the statement later when asked by prosecutors.

The ministry is currently is taking flak for reportedly being lenient toward Korean Air after its initial interviews with the flight crew did not uncover the alleged verbal abuse by the former vice president.

In the meantime, Cho visited the homes of both the staff members again on Monday but in vain. She left apology notes on their doors for the second consecutive day.

“We are out of contact with the flight attendants. Cho will continue to try to offer apologies to them,” said a Korean Air official.

By Lee Ji-yoon (jylee@heraldcorp.com)