A McKinney couple is in jail and a 3-year-old boy is in critical condition after his mother left him with her boyfriend while she was at work.

Police said officers responded to Medical City McKinney hospital on Oct. 14 regarding a 3-year-old brought to the emergency room by his mother's boyfriend, Christopher Alexander. 

Medical staff said the child had serious injuries and was unresponsive when he arrived at the hospital. 

According to an arrest affidavit, Alexander said he found the boy after hearing a thud from another room. The boy had severe brain trauma, bleeding in the brain, bruising all over his body as well as wounds on his chest, stomach and rear. 

Hospital staff told police that the boy's injuries did not match up with Alexander's explanation. 

The boy's mother, Chelsea Berg, said she left her son with Alexander on Oct. 14 before heading to work. She said he called her after lunch saying he was panicked and was taking him to the hospital, according to the affidavit.

Berg was shown pictures of her son and was adamant that he didn't have those injuries when she went to work that same morning.

Police obtained warrants for Berg and Alexander's phones, which revealed text messages talking about bruises and injuries to the boy over a month prior to Oct. 14.

Berg was charged with injury to a child and Alexander was charged with injury to a child and tampering with physical evidence.

The boy was taken to a hospital in Dallas, where as of Oct. 23, he is in critical condition.