A Quincy man was arraigned Tuesday on charges of raping two children and two adults at knifepoint between 2003 and 2006 after DNA testing allegedly matched him to a pair of the assaults, authorities said.
Ivan W. Cheung, 42, was arrested Monday after investigators linked DNA from a cigarette butt he had discarded at the South Bay Mall in June while under surveillance to evidence collected from the most recent attacks, Boston police said.
DNA testing performed at the time had shown the two assaults were carried out by the same person, but authorities could not identify the attacker. Cheung is not included in the national DNA database with profiles of people convicted of violent crimes and sexual assaults.
Authorities declined to say what led them to focus on Cheung, who is also being investigated for sex offenses in Everett and Braintree, according to Boston police reports filed in court.
Cheung was arraigned in Boston Municipal Court on four counts of aggravated rape, four counts of aggravated rape of a child, and two counts of aggravated statutory rape linked to four incidents. A not guilty plea was entered on his behalf.
Judge James M. Martin set bail at $1 million, or $250,000 for each of the four cases.
Cheung worked at State Street Corp. in Boston. The company initially said Cheung had been suspended pending further investigation but later said he had been terminated.
A company spokesman, Edward Patterson, did not provide information on Cheung’s history with the company.
In court, Suffolk Assistant District Attorney Ian Polumbaum said that Cheung was also linked to separate attacks in 2003 based on location and other similarities.
”We allege that the method of the assaults, the sequence of events, is similar enough in the other two cases that we believe it supports charges against the same person,” Polumbaum said.
In four police reports, officials said that on July 31, 2003, Cheung allegedly encountered a 13-year-old girl walking near the intersection of Tremont and Hudson streets in Chinatown. Cheung picked up the girl in his car and forced her to perform a sex act at knifepoint, police said.
The next month, a 14-year-old girl was engaging in sex work near the Liberty Hotel on Beacon Hill when Cheung allegedly got the girl into his vehicle. Cheung then drove to Charlestown, threatened her with a knife, and allegedly raped her in the car, police said. He allegedly raped her a second time in woods near where he had parked, police said.
On Oct 23, 2005, Cheung allegedly met an 23-year-old woman at a bar in downtown Boston. She accepted Cheung’s offer for a ride home, but he drove to an area unknown to the woman, where he allegedly raped and stabbed her, police said. As the woman fought to escape, Cheung allegedly stabbed her again, police said.
The woman was taken to Massachusetts General Hospital, where a rape kit was collected.
The next April, Cheung picked up an 18-year-old woman near the Pizza Regina restaurant in the North End and drove her to Wellesley, where he allegedly raped and stabbed her and dragged her out of his car.
The woman was treated at Newton-Wellesley Hospital, where a rape kit was collected.
“If Mr. Cheung thought that the passage of years had somehow erased the possibility of him facing justice for these vicious crimes, he was very much mistaken,” Suffolk District Attorney Kevin R. Hayden said in a statement.
According to Hayden’s office, the investigation that led to Cheung’s arrest was not related to a statewide backlog of rape kits now undergoing forensic testing; that issue involved only the State Police crime lab, not the Boston Police Department.
“We have no backlog,” said Sergeant Detective John Boyle, a department spokesman.
Cheung will return to court Sept. 22.
Jeremiah Manion of the Globe Staff contributed to this report.