Sixteen years ago, a jury took less than three hours to convict Daniel Dougherty of murdering his two young sons by setting the family home on fire.

A new jury, now hearing his retrial, has deliberated for a day and a half and returns to continue its discussions on Monday.

It was a tense day in Philadelphia Common Pleas Court on Friday, as Judge J. Scott O'Keefe responded to jury matters both straightforward and enigmatic.

A puzzle emerged in midafternoon:

A court crier, who described what occurred under oath, said he answered a knock on the jury door - and the foreman immediately said there was a problem involving one juror.

The foreman told him there was "an incident that maybe find him guilty" - the meaning of that was unclear. The crier said he notified the judge immediately.

The judge called jurors into the courtroom. He asked how they were doing this afternoon. They answered with groans.

The judge told the jury that all questions must be posed in writing, to him, and he then sent the panel back to its deliberations.

Less than an hour later, jurors had a question: Could they have a definition of reasonable doubt?

The judge said that was a doubt that would cause a reasonable, careful person to hesitate before acting in an important matter.

Earlier in the day, the jury asked to see, and was given, photos of the burned living room and dining room of the Oxford Circle rowhouse.

Dougherty, 56, has spent the last 16 years in prison, convicted and sentenced to death in 2000 for killing 3-year-old John and 4-year-old Daniel Jr. in the 1985 fire.

His death sentence was reduced to a life sentence in 2012. Dougherty's retrial came after an appeals court ruled that his original trial lawyer's failings were so egregious that no reliable finding of guilt or innocence occurred.