The judge dismissed the jury after meeting with attorneys about what was called an unforeseen personal issue with Oyler.
The defense has asked for the meeting after some emotional testimony from firefighters who discovered the bodies.
After the meeting, the judge ordered a mental evaluation for the defendant.
Oyler faces a possible death sentence for his 5 first degree murder convictions in connection with the 2006 Esperanza fire.
The 5 firefighters lost their lives when they were overcome by flames as they tried to save a home.
A spokesman for the Riverside County District Attorney's office said a court-appointed psychologist will evaluate Oyler overnight, and report to the court on his findings Wednesday.
On Friday, a jury convicted Raymond Lee Oyler of five counts of first degree murder in the Esperanza Fire. Oyler was also found guilty of 20 counts of arson and 17 counts of using an incendiary device.
Five U.S. Forest Service firefighters were overrun by flames as they tried to save a home. Capt. Mark Allen Loutzenhiser, 43, and firefighters Jason Robert McKay, 27, Jess Edward McLean, 27, Daniel Hoover- Najera, 20, and Pablo Cerda, 24, were killed in the blaze.
Jurors will recommend whether Oyler will face life in prison or the death penalty.
Testimony is expected to last two weeks.
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