Shipping tycoon Angela Chao was drunk when she inadvertently reversed her Tesla into a pond and drowned last month at a Texas ranch, police say.

Blanco County Sheriff's Office found her blood alcohol level was nearly three times the state's legal limit.

The 50-year-old died after dinner on 10 February with a group of friends at the estate near Johnson City.

Her brother-in-law, Senate Republican leader Mitch McConnell, cited the tragedy in his resignation speech.

On Wednesday, Blanco County Sheriff's Office released the findings of its investigation concluding Ms Chao's death was an "unfortunate accident".

She had invited seven girlfriends from her days at Harvard Business School to spend the weekend at the 900-acre ranch.

They had attended a concert by rapper Pitbull in Austin the night beforehand, according to the police report.

After dinner at the guest lodge on the night of her death she headed back to the main house.

But during a three-point turn she accidentally reversed the Model X SUV into a pond.

A friend, Amber Keinan, told detectives Ms Chao had called her at 23:42 and said the car was in the water and she was trapped inside.

"Chao told Keinan the water was rising and she was going to die and said 'I love you,'" the report says. "Chao then said her good byes to Keinan."

The conversation lasted eight minutes.

The police report describes how friends and police tried to save her. Some of the friends were "screaming frantically" at the deputies from the pondside.

Officers eventually smashed the driver's side window of the submerged car, pulling Ms Chao from the vehicle.

She was pronounced dead at 01:40 on 11 February.

A toxicology test found she had a blood alcohol concentration level of 0.233g per 100ml. The legal limit in Texas is 0.08g per 100ml.

Ms Chao was chairwoman and chief executive of her family's shipping business, the Foremost Group, which operates a global fleet of bulk carrier ships. The Chaos have a net worth of $14.2bn (£11bn), according to Forbes.

She was married to Jim Breyer, a billionaire venture capitalist.

Her older sister, Elaine Chao, is married to Mr McConnell and was transportation secretary under President Donald Trump and labour secretary under President George W Bush.

When he announced last month that he was stepping down as Senate minority leader, Mr McConnell suggested the tragedy's impact on his family was a factor in his decision.

"When you lose a loved one, particularly at a young age, there's a certain introspection that accompanies the grieving process," the Kentucky senator said on the floor of the chamber.

Ms Chao's father, Dr James Chao, said in a statement provided to the Austin American-Statesman newspaper: "Angela's passing was a terrible tragedy, and words cannot describe the family's profound grief."