American basketball player Brittney Griner was back in a Russian court Tuesday for her drug possession trial as the United States attempts to negotiate with Russia about her release.

Griner, who plays for the Phoenix Mercury of the Women’s National Basketball Association, was arrested at Moscow’s Sheremetyevo International Airport in February as she was entering the country. She has played for the Russian UMMC Ekaterinburg women’s basketball team during the WNBA’s offseason since 2014.

Russian authorities accused Griner of carrying cannabis in vape cartridges, which is illegal in Russia. During the hearing Tuesday, the prosecution called a narcotics expert to examine the drugs found in Griner’s bag. Her defense attorneys also called an expert who testified the inspection did not follow official rules.

Griner has already pleaded guilty but said she did not know the cannabis was in her bag and was put there by mistake. She said she had no “intention” of breaking the law in Russia. She could face up to 10 years in prison if convicted.

U.S. Secretary of State Antony Blinken spoke to his Russian peer, Sergey Lavrov, last week in an attempt to win the release of Griner and Paul Whelan, an American who has been imprisoned in Russia for espionage since 2018. A phone call between Blinken and Lavrov is the first high-level correspondence between the United States and Moscow since Russia invaded Ukraine in February.

Many observers believe a prisoner trade could be made for Russia arms dealer Viktor Bout, known as the merchant of death, who is currently serving a 25-year sentence in a U.S. prison on charges that include arms trafficking, conspiracy to kill U.S. citizens and officials, and aiding terrorists.

Final statements in Griner’s trial are expected Thursday.

Some information in this report came from The Associated Press.