Prosecutors arraigned the Brooklyn man who allegedly beat his 3-year-old stepdaughter to death and pummeled her brother, the Brooklyn DA's office said.

Kelsey Smith, 20, was charged Wednesday with murder and assault counts via video conference from Bellevue Hospital Center where he is recuperating from self-inflicted wounds. Smith, who was ordered to be held without bail, allegedly killed Jeida Torres and beat her 5-year-old sibling Andrew after he got angry when the girl soiled herself, according to Brooklyn District Attorney Ken Thompson.

"We intend to seek justice on behalf of these two beautiful children" the DA said in a statement.

Smith was watching the kids in their second-floor apartment inside a Bushwick homeless shelter Saturday when the incident took place, police said.

He banged Jeida's head up against a bed frame and choked her, police said. Smith then beat the boy when he tried to intervene, according to investigators.

He fled, but cops found him inside a relative's home in Queens with self-inflicted wounds, police said.

Smith's attorney could not be reached for comment.