On New Year’s Day, Richard Shahan, a children’s pastor at First Baptist Church of Birmingham, checked his baggage at Nashville International Airport and prepared to board a flight to Germany to do missionary work abroad.

But his travel plans were abruptly cut short.

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Red-flagged by security as a flight risk, Shahan, 53, was arrested on the spot. Police claim Shahan was responsible for the brutal July 2013 killing of his wife, Karen, 52, who was reportedly found stabbed on a couch in their suburban Birmingham home, and that he was attempting to flee to Russia.

“He is our only suspect at this time, we’re confident we [have] the person who committed this crime,” Homewood, Ala., Police Chief Jim Roberson says. “Certain inconsistencies … in his interviews kept leading us back to him.”

Although police have yet to announce a possible motive, records show the couple was mired in financial strife, having filed for bankruptcy in February 2010, though a coworker of Karen’s says there were no signs of conflict in their home.

“She was the sweetest human being that walked the face of the earth,” the coworker tells PEOPLE. “She adored her husband, she was proud of his ministries. She was deeply religious. She never said anything negative. I’m still in shock.”

Shahan has told police he was visiting one of his two sons in Kentucky when the crime occurred, and his attorney John Lentine says it’s “absolutely untrue” the pastor was trying to flee. The lawyer says a planned three-year trip to Kazakhstan to help children had been publicly known for some time. He adds Shahan would’ve voluntarily surrendered had they known an arrest was imminent.

The murder has stunned the congregation. Karen, who worked as a manager at an arts and crafts store, was described by another pastor at her memorial service as a devoted Christian, a supportive wife and a loving mother and grandmother.

“All of us were saddened by the unexpected news that Richard Shahan was arrested by Homeland Security just moments before his planned flight departure for Frankfurt, Germany,” his church said in a statement. “There, he was to assume his new role working with the Children’s ministry of Bible Mission International, primarily in Kazakhstan. Our prayers go out to Richard and his family. We trust that eventually truth and justice can prevail.”

Shahan remains in custody in a Birmingham jail while his attorneys seek to free him on bail.