Adriene Williams pleaded on Facebook for her daughter, writing, "Give me my angel back, please" and "Mommy loves you, my angel.

The mother of a 2-year-old girl found dead in a ravine has been arrested on charges she asphyxiated the girl after becoming upset that she had to help the toddler clean herself after using the toilet, police said Tuesday.

Adriene Williams, 26, of Wilkinsburg, was arrested on charges of criminal homicide, endangering the welfare of a child, tampering with evidence and abuse of a corpse, Allegheny County police said. Online court records didn't list an attorney for her.

Her toddler, Adrionna, was discovered dead by a dog walker in a neighboring suburb, Swissvale, about 40 minutes after her family reported her missing June 14.

The morning after Adrionna's body was found, Williams pleaded on Facebook for her daughter, writing, "Give me my angel back, please" and "Mommy loves you, my angel." The girl's death also prompted a march several days later, as community leaders decried the crime and asked for the public's help.

But according to the nine-page criminal complaint, police charged Williams because items found in her car, and cellphone records and surveillance video, strongly suggest she's the killer.

The complaint also revealed for the first time that the medical examiner determined the girl was asphyxiated, though investigators didn't say specifically how that occurred.

The girl's bare feet gave no indication she had walked to where she was found, about 2 miles from her grandmother' duplex, police said.

The girl was supposed to be staying at her grandmother's while her mother worked the 7 pm to midnight shift as a security guard at a low-income apartment complex in Pittsburgh, the complaint said.

The complaint spells out a series of interlocking pieces of physical and circumstantial evidence.

Among other things, police found several colored paper clips near the dead girl's body that were similar to clips later found in Williams' car. Also found in the car were small splotches of mud and Williams' uniform shirt, on which police found the girl's DNA and stains from watermelon a treat the girl was eating just before her mother left for work.

Police believe Williams left for work about 6:20 p.m. only to have the girl follow her out onto the porch. Nobody else saw what happened after that, though the girl's grandmother, aunt and two cousins at the duplex all assumed Williams left for work, police said.

Shortly before Williams left, her daughter used the bathroom and needed help cleaning herself, according to one cousin.

"This seemed to annoy Adriene and she got up from the couch stating, 'I want to change my name,' in a loud angry voice," the cousin told police. After Williams helped her daughter, the girl climbed on a couch to play with her mother but the cousin told police, "it seemed that Adriene didn't want to play with her."

Police found Williams didn't answer more than 20 calls from the girl's grandmother and cousin and responded to just one of 10 text messages from them during a 40-minute period after the relatives couldn't find the girl.

Surveillance video from various sources, meanwhile, showed Williams' car headed toward the area where the girl's body was later found and not toward her workplace several miles away. Cellphone tower information painted a similar picture, police said.

Williams told police she left her daughter behind as she headed for work, and didn't return home until a text message from her daughter's cousin told her the girl was missing.