WHEATON -- The only person who knows why Brian Dugan confessed to murdering Jeanine Nicarico is Brian Dugan himself.

This week, however, prosecutors and defense lawyers tried to draw their own conclusions in front of jurors who will decide if Dugan receives a death sentence for the Naperville girl's February 1983 murder.

Prosecutors told jurors Thursday Dugan's "confession" to Nicarico's murder was used by defense attorneys as bait to spare the career criminal life on death row for the murders of 27-year-old Donna Schnorr of Geneva and 7-year-old Melissa Ackerman of Somonauk.

DuPage County State's Attorney Joseph Birkett said Dugan's admissions were made solely for plea bargaining purpose and not out of good faith, as his defense would argue.

Defense lawyers have said a handwritten statement made by Dugan before he was even a suspect in the murder proves that Dugan's confession stemmed from not wanting to see two men sit on Illinois death row for crimes he committed. Alex Hernandez and Rolando Cruz, two Aurora men, already had been charged with and convicted of Nicarico's death.

George Mueller, Dugan's former attorney, took the stand Thursday and told jurors that the handwritten, notarized confession Dugan had given in 1985 was drafted at Mueller's request after he found out about Dugan's crime. Though the information was protected by attorney-client information, in the event of Dugan's death, Mueller wanted to have solid proof of the Nicarico murder admissions.

"Every statement was authorized for the sole purpose of achieving a plea agreement, correct?" Birkett asked.

That letter, which switched attorney hands several time over the years, was just made public in August.

It reads that it was written by oral agreement at his lawyer's request to obtain a plea agreement, or "to ensure innocent people are not murdered by the state for crimes they had no part in."

"Brian and I both knew that getting Cruz and Hernandez off would be a good thing for them," Mueller said. "But the purpose (of the letter) was to get a natural life sentence."

Dugan has remained adamant about his desire for an additional life sentence and cooperated with authorities in hope of being spared the death penalty.

Jurors will have to decide if Dugan will be sentenced to death or whether Dugan's confession, and the subsequent release of Cruz and Hernandez, are compelling enough reasons for mercy.

Jurors will be back in court on Tuesday.