City prosecutors plan to drop charges against a man originally charged in the slaying Sunday of his 3-year-old stepdaughter after police learned of additional evidence and arrested another man in the killing.

Detective Gordon Carew said the victim's stepfather, Nicholas Dieter, 21, of Forest Hill, Harford County, is to be released and will have charges dismissed in the killing of Calen Faith Dirubbo in the girl's home in the 2500 block of Moore Ave.

Carew said Calen had been beaten and was dead or dying when Dieter, who is estranged from the girl's mother, arrived at the house Sunday evening to watch the girl.

The girl's mother, Cheryl Dieter-Dirubbo, 24, and her live-in boyfriend, Eric Stoddard, 20, had gone out for the evening.

Dieter dialed 911 Sunday night when he found the girl unresponsive, and she was pronounced dead at the scene. Dieter was charged Monday after an autopsy showed the death was a homicide.

"Everything we knew at that time pointed to Mr. Dieter," said Carew.

But Carew said that he uncovered additional information and that Stoddard was charged with first-degree murder and first-degree assault Tuesday at police headquarters after an interview.

Carew declined to elaborate.

Stoddard is being held without bail at Central Booking and Intake Center.