Prosecutors appear to have reopened an investigation into a complex cash and real estate deal apparently involving the family of the late former President Roh Moo-hyun, as a Korean-American woman underwent three days of questioning over allegations Roh's daughter bought her New Jersey apartment years ago with cash from suspicious sources.

The Korean-American, named Gyeong Yeon-hee, 43, reportedly arrived in Seoul Sunday and has been quizzed by prosecutors over the probe, which revisits suspicions that Roh's only daughter, Jeong-yeon, bought what is known as a "Hudson Club" apartment in 2009 with money allegedly provided by a Busan-based businessman, Park Yeon-cha.

"Gyeong has been summoned today for the third consecutive day," said a prosecutor at the Supreme Prosecutors' Office.

"She was allowed to return after being asked some simple questions," the prosecutor said, refusing to elaborate due to the political sensitivity of the case.

Park, who was sentenced last December to two years and six months in jail on charges of offering bribes and tax evasion, was at the center of a massive bribery scandal that prompted an investigation of the late president and his family. At the height of the prosecutors' investigation, Roh took his own life in May 2009 by jumping off a cliff behind his retirement home in southeast Korea.

Prosecutors closed the investigation shortly after Roh's death but reopened it in late February. They suspended the investigation again in March ahead of April's general elections as Gyeong, a key witness, had refused to come to Seoul.

Prosecutors have so far discovered Gyeong received payment for the apartment via two brokers. One of the two, a dealer of foreign cars, is suspected of using illicit means to exchange 1.3 billion won (US$1.1 million) into U.S. dollars to send to Gyeong.

Prosecutors suspect the money was the last installment for the sale of the New Jersey apartment. (Yonhap)