Former Doosan Bears infielder Oh Jae-won, second from left, who faces drug charges, leaves the Seoul Gangnam Police Station, March 29, to be transferred to the prosecution. Yonhap

Police are investigating 13 former and current baseball players suspected of being prescribed sleeping pills and handing them to former Doosan Bears infielder Oh Jae-won, who is currently on trial on drug charges after being arrested in March.

Seoul Metropolitan Police Agency Commissioner Cho Ji-ho said in a press briefing Tuesday that the 13 include eight current Doosan Bears players the team reported to the Korea Baseball Organization's Clean Baseball Center, which monitors player misconduct.

As most of the involved players are reportedly on the reserve team, some allege that Oh may have forced them to obtain the psychotropic medications on his behalf while he was still on the team.

"That possibility will be taken into consideration in the final stage of the investigation," Cho said.

Oh is facing charges of taking methamphetamine 11 times from November 2022 to November 2023, as well as receiving 2,242 Zolpidem sleeping pills from acquaintances from January 2023 to March this year and habitually taking them.

During his first hearing on May 1, Oh admitted to drug use.

On May 3, prosecutors indicted him with additional charges of receiving 0.2 grams of methamphetamine from his acquaintance last November.

The acquaintance, identified as Oh's drug supplier, was also indicted on charges of handing over methamphetamine to Oh and selling 400 sleeping pills to him.

"We will closely cooperate with police and continue to investigate the case to see if there are additional accomplices or other crimes," a prosecutor said.

Oh was arrested on March 22 after the Seoul Central District Court issued an arrest warrant for him, citing flight risk.

Police opened the investigation into his suspected drug use earlier that month following a tipoff from one of his female acquaintances.

The 39-year-old spent his entire career with the Bears, helping the squad to win three Korean Series titles in 2015, 2016 and 2019.

He also helped the Korean national team to gold medals at the 2014 Asian Games and the 2015 World Baseball Softball Confederation Premier12.

He retired from professional baseball in 2022.