Donald Trump's older sister has been sent a threatening letter just 24 hours after his eldest son Eric received a suspicious package.

Federal appeals court judge Maryanne Trump Barry discovered the note at her home in Philadelphia on Friday, prompting police to investigate.

There was no white powder in the envelope, but the threat was similar to that sent to Eric, NBC reported.

It is not clear whether the mail was sent by the same person.

Trump Barry is a 78-year-old judge with the U.S. Circuit Court of Appeals for the 3rd Circuit who Ted Cruz has described as the GOP candidate's 'partial-birth-abortion-supporting sister'.

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Donald Trump's older sister, Federal appeals court judge Maryanne Trump Barry (right), has been sent a threatening letter just 24 hours after his eldest son Eric received a suspicious package

There was no white powder in the envelope, but the threat was similar to that sent to Eric (right). It is not clear whether the mail was sent by the same person.

Police were called to Eric Trump's (left) New York home after his wife Lara Yunaska (right) opened a package and a white powder fell out

More than two dozen cops were seen inside the Central Park South address late Thursday. Above, the apartment building Thursday night

Police were called to the apartment of Donald Trump's son Eric on Thursday after his wife opened a letter and white powder fell out, WABC reported.

Inside the letter postmarked form Massachusetts was also a note threatening harm to Trump's five children if he does not pull out of the presidential race.

Eric Trump and his wife Lara live at Trump Parc East, one of Trump's luxury buildings on the southern edge of Central Park.

More than two dozen cops were seen inside the Central Park South address late Thursday.

After tests, the NYPD reportedly found nothing hazardous.

The letter arrived at Eric Trump's apartment the same day the hacker group Anonymous released his father's phone number and social security number in a targeted cyber attack.

Eric has been a staunch supporter of his father as he bids to become the Republican nomination for President.

He was in Florida when he won the state's primary, and knocked Marco Rubio out of the race.

The 32-year-old is the youngest of The Donald's three children with first wife Ivana Trump.

He is the executive vice president of development and acquisitions at the Trump Organization.

The businessman got married to CBS News producer Lara Yunaska in 2014.

It's not known whether he was at home at the time.