The prosecution named Lee as a suspect on Wednesday and is investigating whether 30 billion won ($25.28 million) provided by Samsung to a business and foundations backed by Park's friend, Choi Soon-sil, were connected to a 2015 decision by the country's national pension fund to support a controversial merger of two group affiliates.
"I am very sorry to the South Korean people for not showing a better side," Lee told reporters after arriving at the office in a black Korean-made Ssangyong sedan, greeted by protesters holding signs calling for his arrest and accusing him of being an accomplice to President Park.
Wearing a dark suit, white shirt and dark red necktie, Lee bowed after making his brief remarks to a crowd of journalists.
Park could become South Korea's first democratically elected leader to leave office early after parliament voted in December to impeach her over the corruption scandal. The impeachment must be upheld or overturned by the Constitutional Court.
The scandal has triggered big weekly rallies calling for Park to step down.Read more at Reuters