NEW YORK (AP) — During a yearslong court fight over an idiosyncratic copper heiress' $300 million estate, a criminal investigation quietly examined how she and her finances were being looked after, though no one was ever charged.

The probe's end became public Thursday, when the Manhattan district attorney's office confirmed its investigation into Huguette Clark's circumstances had wrapped up.

"The case is closed, barring any new information," spokeswoman Erin Duggan said in a statement after NBCNews.com first reported the development.

It's not immediately clear when the investigation wrapped up. It spanned two or more years around Clark's 2011 death, according to a law enforcement official who wasn't authorized to discuss the details and spoke on condition of anonymity.

Clark died at 104, the youngest daughter of Montana copper baron and U.S. Sen. William A. Clark, who founded Las Vegas. She had elected to spend her last 20 years in a hospital, despite being well enough most of that time to live in her massive Fifth Avenue apartment. She also had mansions in Santa Barbara, Calif., and New Canaan, Conn.

The DA's investigation began in 2010, two people familiar with the matter said at the time, speaking on condition of anonymity because they weren't authorized to speak publicly about it.

Some of the childless Clark's distant relatives had started questioning how her lawyer and accountant were handling her affairs. The two professionals were eventually prohibited from administering her estate after officials said they had underpaid her taxes by $90 million; they have denied wrongdoing.

That was followed by civil court clashes over her will — she had signed two starkly different ones within six weeks when she was 98 — and over hefty gifts she gave during her lifetime to the hospital, nurses, doctors and others who worked and cared for her.

Her relatives said the caregivers and advisers manipulated Clark. The beneficiaries said the heiress was purposefully generous to those in her daily life.

The will contest was settled this September with a deal that mainly benefited the relatives and arts institutions. But a $100 million lawsuit against the hospital and a doctor continues.

Prosecutors apparently didn't find evidence beyond a reasonable doubt that anyone's conduct toward Clark had been criminal.