Springfield Bishop Thomas John Paprocki, in a letter to parishioners of St. Mary's Church, acknowledged that the Rev. Piotr Kosk faces a church investigation into his behavior as well as possible financial misconduct.
Paprocki said he could petition the Vatican to have Kosk removed from the priesthood.
In his letter, Paprocki said that Kosk and Deacon Stefan Kaniewski admitted they had been a years-long relationship that also involved the use of illegal drugs.
Kaniewski, who attends St. Meinrad Seminary in Indiana, has requested dispensation from the clerical state, Paprocki wrote.
Kaniewski is also a native of Poland. He was ordained a transitional deacon, the last step before priesthood, by Paprocki in May.
"I am aware the information I am sharing with you is both shocking and scandalous," Paprocki acknowledged. "Please know that I share your surprise and dismay.
"A deep and sacred trust has been violated."
Kosk came to the U.S. from Skwierzyna, Poland, in 2016, according to a biography Kosk provided to parishioners when he was serving at St. Paul Parish in Highland. He was ordained a priest in 2020.
Kosk also had ministerial duties at parishes in Kincaid and Stonington. He served as a chaplain at Taylorville Correctional Center.
The Rev. John Burnette is serving the three parishes.
Paprocki urged anyone who has knowledge of financial misconduct or adult sexual misconduct committed by priests, deacons, or lay employees of the church to call the diocese's hotline number at 1-866-346-2003
David Clohessy, a volunteer director of Missouri Survivors Network of those Abused by Priests (SNAP), said virtually any seminarian is extremely vulnerable to sexual exploitation and abuse by a priest and often "consent" to sex with an abusive cleric because they desperately want to be ordained and fear retaliation if they resist such advances.
"Now it's crucial that (Bishop Paprocki) use his vast resources to beg anyone else who may have been hurt by this priest to contact law enforcement and get help from independent sources, like therapists, loved ones and support groups like (SNAP)," Clohessy said.