An Illinois man was found guilty Thursday of killing his parents and three teenage sisters at their southeastern Iowa home last fall.

Judge Michael R. Mullins read the verdict in Van Buren County District Court. The courtroom was packed with about 100 family members and others.

Prosecutors argued that Shawn Bentler, 23, wanted to inherit money from the family's successful grain elevator and lumberyard businesses. They said that led Bentler to shoot his parents, Michael and Sandra, and teenage sisters, Sheena, Shelby and Shayne, with a .22 caliber rifle in the early morning hours of Oct. 14, 2006.

Prosecutors focused on a 911 call made from the Bentler home the night of the slayings. The call begins with Shayne saying her older brother was "going to do something," followed by the sound of his mother screaming, a gunshot and a scream "Shawn, no!" before the line goes dead.

"A mother and sister would almost certainly not mistake their son and brother as the murderer," the judge said.

Defense lawyers tried to show that Bentler got along with his family, and that he could not have traveled from his home in Quincy, Ill., to the family's home in Bonaparte and back in enough time to kill them. They had used Bentler's roommate —who said he saw Shawn hours before and after the slayings — in presenting an alibi.

"There was an adequate window of time ... to commit the crimes and return to Quincy before he was next seen by" his roommate, the judge said.

Bentler took the stand during the trial earlier this month, repeatedly denying that he killed his family. He reminisced about holding each of his sisters at their births, described a bond with his mother and spoke proudly of his father.