"We believe the evidence in the case supports the scenario that Casey Anthony chloroformed Caylee so that she would not suffer, placed duct tape over her nose and mouth…and then disposed of her body," Ashton said.
Ashton also said it was "absurd" for the defense to argue that Caylee accidentally drowned in the family pool and that George Anthony, Casey Anthony's father, helped dispose of the body.
"Any way you slice it...Casey Anthony is guilty of murder in the first degree in this case," Ashton said.
The prosecution poked holes in the defense's claims that George Anthony tried to implicate his daughter to deflect blame from himself in the alleged cover-up.
On Sunday, defense attorney Baez portrayed George Anthony as a selfish man, saying repeatedly, "George only cares about George." Baez and his defense team attempted to undermine a suicide attempt that George Anthony painfully described on the witness stand last week.
"If he really wanted to kill himself, he could have," Baez said on Sunday.
George Anthony attempted suicide in January 2009, just weeks after Caylee's remains were found. Today, the prosecution read portions of George Anthony's suicide note to jurors.
"George is not this Machiavellian self-interested monster that counsel has suggested," Ashton said. "To denigrate that pain by suggesting that that is an insincere selfish, self-serving statement, I believe, belies the facts."
Defense attorney Baez at times raised his eyebrows and shook his head as the prosecution delivered their rebuttal.
On Sunday, Judge Perry reprimanded both Ashton and Baez after Baez interrupted his summation and yelled to jurors that prosecutor Jeff Ashton was a "laughing guy" as Ashton barely hid a smile behind his hand.
Perry threatened to expel attorneys from the courtroom if the gamesmanship continued.