US basketball star Brittney Griner has urged fans to write letters to Paul Whelan, a former US Marine held in Russia, days after she was released from a Russian prison in a prisoner swap, Reuters reported.

The two-time Olympic gold medalist and eight-time All-Star of the Women’s National Basketball Association (WNBA) was arrested in February at an airport outside Moscow for carrying hashish oil cigarette cartridges in her luggage.

“Thanks to the efforts of many, including yours, I am home almost 10 months later,” Griner wrote in a letter posted on her Instagram account.

“Your letters helped me to not lose hope at a time when I was full of regret and vulnerable in a way I could never have imagined,” she said.

US officials said they had pushed for the release of both Griner and Whelan, who is being held on what Washington called trumped-up espionage charges, but Moscow took a different view of Whelan.

Whelan expressed concern that more had not been done to secure his release, and Republican lawmakers criticized Democratic President Joe Biden, who said the United States would not give up trying to secure his freedom.

Griner said the letters he received show “the power of collective hands.”

“Too many families are left with loved ones wrongfully incarcerated,” wrote Griner, who left Brooke Army Medical Center last week and said she plans to resume her WNBA career next season.

“I hope you will join me in writing to Paul Whelan and continue to advocate for other Americans to be rescued and returned to their families,” she added.