Assistant District Attorney Lorraine Donnelly asked Common Pleas Court Judge Benjamin Lerner to sentence Merle to 15 to 30 years in prison.
Donnelly referred to Merle's long history of arrests and that he had a cache of heroin and the gun hidden in the sofa. She called Merle "beyond rehabilitation."
Defense attorney Jeremy-Evan Alva asked Lerner to sentence Merle to slightly more than the mandatory minimum sentence of 5 to 10 years.
Alva noted that Merle is being treated for depression involving his son's death: "No matter how much time he is serving, he is going to be serving a life sentence."
Alva said the death has "torn these families apart."
Lerner cut off the defense lawyer.
"I'm not impressed," the judge said and told the weeping family that the boy's death was partly the result of their tolerating Merle's drug dealing from his home in the 600 block of East Clementine Street.
"It's too bad it took the death of this little child to tear them apart," Lerner said. "If there had been a little less tolerance . . . maybe that child wouldn't be dead and we wouldn't be here today."
In an earlier hearing, Donnelly said Merle sold heroin from his house and had a 9mm pistol - its serial numbers obliterated - hidden with his stash of heroin in a sofa cushion.
About 4:30 p.m. July 14, 2011, Donnelly said, Merle was home playing a video game with his son while a 1-year-old girl slept upstairs.
Donnelly said Merle's brother-in-law, Edgar Perez, came to the door to say that Merle's wife, Yesenia Perez, was arguing with neighbors. Edgar Perez grabbed the gun from the sofa and took it to the confrontation. Merle followed, leaving the children unattended.
At some point during the argument, Donnelly continued, Edgar Perez's brother Brandon took the gun back to the house and put it back in the sofa.
Donnelly said all the adults were outside when they heard what they thought was a firecracker. Fifteen minutes later, the parents found Javier Jr. on the floor with a gunshot wound to his face and the gun at his feet.
The Perez brothers were also charged in the boy's death. Edgar Perez, 23, pleaded guilty to firearms charges and was sentenced Jan. 4 to 26 to 52 months in prison.
Brandon Perez, 20, pleaded guilty to involuntary manslaughter and gun charges and will be sentenced Feb. 14.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.