Joseph Smith asked Judge Andrew Owens to sentence him to life in prison, saying he did not care whether he lives or dies but does worry about the effect of his crimes on his children, CNN reported.
"I never expected or believed I could commit this horrible crime. I can only hope that I can be an example to others," Smith said.
The jury that convicted Smith of the murder of Carlie Brucia recommended a death sentence. Owens said he will make the final decision by March 15.
Smith's testimony and arguments from a prosecutor and defense counsel ended a two-day hearing. On Monday, Carlie's aunts and the mother of her best friend described the impact of the crime.
Her mother, who is being held in Tampa on drug charges, submitted a written statement.
Smith said that his own drug use destroyed his marriage. He said he killed Carlie on the day his wife told him she would not take him back.