Hilary Duff paid tribute to her ex-boyfriend, singer and former child star Aaron Carter, after the latter reportedly passed away on Saturday.

On Instagram, Duff wrote: ““For Aaron– I’m deeply sorry that life was so hard for you and that you had to struggle in-front of the whole world.”

“You had a charm that was absolutely effervescent…boy did my teenage self love you deeply. Sending love to your family at this time. Rest easy,” she added.

Duff starred with Carter in the Disney Channel series “Lizzie McGuire.”

View this post on Instagram

A post shared by Hilary Duff (@hilaryduff)

Singer Billy Gilman said the passing of Carter, whom he regard as his brother, "gutted" him but added it is time for the "musical genius" to rest.

"The amount of times I reached out as a brother to see if he was ok I can't begin to count. You were truly a musical genius and could never just be that," said Gilman.

"I have no words. All I can say is I know what you had to deal with since we first met in 2001," he added.

"You can now rest. Forever a brother to me. Love you, Aaron."

Entertainment outlet TMZ reported that the brother of Backstreet Boy Nick Carter was found dead in his tub at his residence in Lancaster, California.

A police spokesperson told AFP that officers responded to Carter's home at 10:58 a.m. and found a deceased body, but were not yet able to publicly identify the person.

Carter's manager did not immediately respond to an AFP query.

The artist born December 7, 1987 in Tampa, Florida began performing at age seven, releasing his debut album at age nine in 1997.

His sophomore effort "Aaron's Party (Come Get It)" sold three million copies stateside, propelling him to teen heartthrob status. He became a regular on preteen Nickelodeon and Disney shows, including an appearance on the popular "Lizzie McGuire."

Carter toured with the boy band The Backstreet Boys -- his elder brother is a member -- as well as Britney Spears, and saw his next album, "Oh Aaron," go platinum.

As he aged, the musician's star began to fade but Carter remained in the public eye, appearing on a number of reality shows and off-Broadway productions, and releasing some new music online.

But his personal life struggles became tabloid fodder, including apparent strife among the five Carter siblings and family fights over money.

In 2011, it was revealed that Carter had entered a treatment facility, with the star telling his fans that "the main thing in life is not to be afraid of being human."

After leaving rehab, the artist began doing one-off shows, and later a Canadian tour. He released another album in 2018.

He had filed a bankruptcy petition in 2013 over millions in debt, much of it tax-related. Carter also faced several run-ins with the law primarily over possession charges and reckless driving.

In 2017, he began to discuss publicly his arrests and skinny appearance that had fueled rumors of illness or illegal drug use.

He admitted himself to another treatment center over prescription drug use aimed at anxiety and sleep issues, reporting improvement in 2018.

Earlier this year, he told the Daily Mail he vied to no longer be seen as a "train wreck."

"I am not how some people try to paint me," he told the outlet. "If somebody wants to call me a train wreck, well I've been a train that's been wrecked multiple times and derailed by many different things." — With AFP