PHOENIX, AZ - SEPTEMBER 5: Brittney Griner #42 of the Phoenix Mercury looks on before the game against the Washington Mystics on September 5, 2023 at Footprint Center in Phoenix, Arizona. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, user is consenting to the terms and conditions of the Getty Images License Agreement. Mandatory Copyright Notice: Copyright 2023 NBAE (Photo by Kate Frese/NBAE via Getty Images)Kate Frese/NBAE via Getty Images

Phoenix Mercury star Brittney Griner shed light on the conditions of her confinement in Russia after being wrongfully detained at a Moscow airport in February 2022.

Good Morning America shared a portion of Griner's interview with Robin Roberts, which is scheduled to air Wednesday night.

Part of the interview included Roberts narrating footage of Griner's arrest, with Griner providing her recollection of the event. She lamented being "absent-minded" and making the "huge mistake" of leaving two vape cartridges in her luggage.

Good Morning America @GMA

EXCLUSIVE: Brittney Griner tells <a href="">@robinroberts</a> about the guilt she felt after she was arrested in Russia: "I let everybody down."<br><br>"Prisoner in Russia: The Brittney Griner interview" airs tonight on ABC 20/20 and later on Hulu. <a href="">#BrittneyGrinerOnABC</a> <a href="">

Upon entering custody, the 33-year-old told Roberts she "felt less than a human" when discovering her new living conditions.

"The mattress had a huge blood stain on it," she said.

Among the other features were a bed that was too small for her 6'9" frame with "thin" sheets and toothpaste that was expired to the point where prisoners used it to kill black mold on the prison walls.

Griner's noticeably shorter hair upon her release was also due to her stay in a different prison. She told Roberts she cut her dreadlocks because spiders were living above her bed and her hair would freeze, making her sick.

Officials from the Biden administration secured Griner's release in December 2022 as part of a prisoner swap involving international arms dealer Viktor Bout.

A few weeks after setting foot on American soil, she advocated for the release of Paul Whelan. Whelan, a former U.S. Marine, received a 16-year prison sentence on espionage charges in 2020.

Griner told Roberts she was disappointed to discover Whelan wasn't joining her on her flight out of Russia.

The eight-time All-Star didn't waste any time returning to a WNBA court, suiting up for the Mercury in 31 games last season. She averaged 17.5 points, 6.3 rebounds and 1.6 blocks.

A free agent this offseason, Griner signed a one-year deal to return to Phoenix.