Mr. Tsai was taken to Elmhurst Hospital, where detectives from the 83rd Precinct visited him the next day. Unable to speak, he wrote that his wife wanted him dead so she could control the hosiery business that they shared, instead of dividing up the property in divorce court. He died 11 days after the shooting.

The couple left a trail of their enmity in divorce papers, filed by Mr. Tsai in October 1986. The records detail their dispute over millions of dollars in business proceeds and properties; a bitter custody battle over their son, Steven, then a toddler; and violent fights that brought the police to their house in Jamaica Estates.

An investigative firm, F.T.I. Global Risk and Investigations, which the university hired to conduct a forensic examination of Dr. Chang’s expense accounts and other records, referred its findings to the Queens district attorney, Richard A. Brown, in April 2010 and strongly urged another investigation of Mr. Tsai’s killing, on the theory that Dr. Chang had a role.

One investigator who sifted through her 80 boxes of files said that more than a third of it was relevant or contained incriminating evidence linking her to the homicide of her first husband, the attempted bribery of Taiwanese officials in 2003 and the almost routine fraud that was detailed in her expense accounts. The investigator spoke on condition of anonymity because he was not authorized to speak about the case.

In 2001, she began spending more time at Foxwoods, where she found solace at the baccarat tables, drinking Hennessy at dinner and coffee at the high-stakes tables. A federal agent testified at her trial that Dr. Chang would call her office at St. John’s from a casino suite and request bank withdrawals just shy of $10,000, the amount at which financial institutions must report a transaction to the government. The agent, Kenneth Hosey, said that students would come to Connecticut to deliver the money, and that she subsequently bought into casino games for the same amounts.

When a prosecutor asked her in court about the transactions, Dr. Chang said that they were intended to bring good fortune; the dollar amounts coincided with her lucky numbers: nine, eight and six. People at Foxwoods remembered that she lent as much as $30,000 to fellow gamblers, and that she favored a dubious wagering strategy: doubling her bet each time she lost.

In 2010, Dr. Chang was indicted in Queens. When she tried to use her house as bail collateral, Mr. Pavlides argued that the mortgage was paid off with a $300,000 check from her second husband, Danny Lau, whose own lawyer, Mr. Pavlides explained, admitted that the money came from criminal ties.