Koster retired in 1996 and died at the end of May at age 94, according to his obituary. He was not among the 28 priests the Sioux City Diocese identified earlier this year as being credibly accused of sexual abuse, dating to the 1940s. 

Diocese spokeswoman Susan O'Brien said in an email Friday night that she could not specifically comment on Heinrich's allegations. 

"The Diocese of Sioux City hopes all victims of clergy sexual abuse continue to come forward, contact authorities and our victim assistance coordinator to file a report," O'Brien said in a statement. "We want victims of clergy sexual abuse to know we are committed to moving forward with openness and accountability."

O'Brien encouraged anyone wishing to file an abuse report to visit a Diocese website set up for that purpose: scdiocese.org/how-to-report-suspected-abuse. 

During his career, Koster served at parishes throughout Iowa, including at St. Mary’s in Danbury, St. Mary’s in Doon, Sacred Heart in Templeton, St. Mary’s in Armstrong, St. Cecelia’s in Algona and St. Joseph’s in Carroll, among others, according to his obituary. 

Heinrich, who now lives in California, was a student at the Our Lady of Mt. Carmel grade school when Koster was the head of the school, according to the lawsuit. The abuse occurred when Heinrich was in the fourth and fifth grade, and subsequently recurred when he was in the eighth grade. 

Heinrich attempted to avoid Koster as time went on, but this only angered Koster, according to the suit. During a physical education class, Koster allegedly arranged a boxing match between Heinrich and the "biggest boy" in the class, and the mismatch left Heinrich "physically and emotionally beaten."

Heinrich "took that beating to be a warning as to the consequences of any further perceived insolence against the authority of Fr. Koster," according to the suit.

"Koster used his status and substantial power as a priest to groom (Heinrich) for sexual abuse, to convince plaintiff that the abuse was normal, to convince him that reporting his abuse would be futile and to sexually abuse him," the lawsuit said.

Koster allegedly told Heinrich "that sexual activity between an adult man and a child was 'normal' and 'what God wants.'" He also told Heinrich that he was a "bad boy" and that no one would believe him if he told anyone of the abuse, according to the suit. 

The suit alleges the Diocese and the church "knew or should have known of Koster's sexual abuses" and "did nothing to stop the abuse or to warn vulnerable parishioners." 

The alleged abuse left Heinrich with "incapacitating anxiety" -- he reportedly developed an ulcer in the fifth grade -- and he continues to suffer serious emotional distress, embarrassment, shame, humiliation, guilt, loss of self-esteem and depression. In addition, he lost his job and "ability to be gainfully employed" and is now incurring expenses for psychological treatment, therapy and counseling.

The suit seeks unspecified compensatory and punitive damages from the Diocese. 

Aiming to "shine a light" on its own "shameful history," the Sioux City Diocese made public in February the names of 28 priests credibly accused of sexually abusing more than 100 children while serving the Northwest Iowa diocese. Unlike some other Catholic dioceses, Sioux City had never before released such a list of priests, despite repeated calls from victims and advocacy groups to do so.

A Diocesan Review Board and the diocese's law firm reviewed priest files dating to the diocese's founding in 1902, with the first accusation deemed credible occurring in 1948, and the most recent in 1995. The board said it considered factors such as physical evidence, witness testimony, accuracy of details, and corroborating evidence from files or other witnesses.