(CNN) -- A Philadelphia jury was unable to reach a verdict Wednesday on four of five charges in a landmark priest sex abuse case, according to a source familiar with the proceeding.
There appear to be two holdouts, and the judge has ordered jurors to keep deliberating, the source said. It is not clear which charges could not be agreed upon.
Common Pleas Court Judge M. Teresa Sarmina said the panel says it has developed "firm, fixed opinions" and "entrenched positions," rendering it unable to return a verdict after 12 days of deliberations.
Monsignor William Lynn is considered the first high-ranking church official to be charged in the three-month-long trial.
Lynn, 61, is accused of knowingly allowing dangerous priests to continue in the ministry in roles in which they had access to children. Also on trial is the Rev. James Brennan, 48, who is accused of the attempted rape of a 14-year-old boy. Both Brennan and Lynn have pleaded not guilty.
As the secretary for clergy in Philadelphia from 1992 to 2004, Lynn was responsible for the personnel matters of the more than 800 priests in the Philadelphia Archdiocese, including investigating child sex abuse allegations against priests.
Lynn's defense team argues that he repeatedly sent word of child sex abuse up the chain of command, operated under strict orders from the late Archbishop Cardinal Anthony Bevilacqua and never had the power to remove a priest from ministry.
Following his post as secretary for clergy, Lynn became pastor of a Philadelphia-area parish until he was removed after his arrest as a result of a February 2011 grand jury report.
Another priest, the now-defrocked Edward Avery, pleaded guilty in March after admitting to sexually assaulting a 10-year-old altar boy during the 1998-1999 school year.
The 2011 report led the Philadelphia district attorney's office to criminally charge four Philadelphia priests and a parochial school teacher with raping and assaulting boys in their care, while Lynn was accused of allowing the abusive priests to have access to children.
On May 4, Archbishop Charles J. Chaput announced resolutions to eight of the 26 cases of priests on administrative leave as a result of the grand jury report.
The archdiocese also announced it ousted two priests -- not connected to those cases -- because of allegations of sexual abuse of minors.
The trial marks the first time U.S. prosecutors have charged not just the priests who allegedly committed the abuses, but an official who stands accused of failing to stop the assaults.
CNN's Susan Candiotti and Sarah Hoye contributed to this report.