When he went outside about 15 minutes later to check on her, she was gone.
Mathews was most recently seen wearing a pink best, dark pajama bottoms and pink flip-flops.
"That does not seem like a normal response that one would do if you have a missing child", said Sgt. Kevin Perlich.
Sherin's father, Mathews, 37, was arrested on Saturday on a charge of abandoning or endangering a child.
Police say Mathews is required to wear an ankle monitor.
Police say the parents are no longer cooperating with the investigation.
According to CBS Dallas, the mother and father have hired their own lawyers.
"It just makes me sick", said one woman who travelled from Red Oak to help search.
Fetus kicks through uterine wall
She and her child are in stable condition, said the Peking University Shenzhen Hospital in southern China, MailOnline reported . Zhong Shilin, Ms Zhang's doctor, claimed to have found a 7cm-long (2.8 inches) rupture on Ms Zhang's uterus.
Kochi police is clueless as new reports emerge linking the parents of missing three-year-old Indian girl child in Texas, United States, to Ernakulam as their base. Both parents have retained attorneys - Sherin's mother was not accused of any wrongdoing, while her father had not yet entered a plea in relation to charges leveled against him.
Wesley told investigators he left Sherin, his adopted daughter, alone behind the house by a tree Saturday morning.
Investigators have seized three vehicles, cellphones and laptops from the family in an effort to find out what became of Sherin, Perlich said. Authorities are also reviewing footage from nearby surveillance cameras.
Anyone with information about Sherin Mathews or her location was asked to contact the Richardson Police Department at 972-744-4800.
According to NBC 5, Texas Child Protective Services removed the toddler's 4-year-old sister from the family Monday and placed her in protective custody as police continue to search for the missing child. A CPS spokeswoman, Marissa Gonzales, said the agency has had dealings with the family before, but she declined to release additional information.
According to NBC, Williams was adopted by the Mathews family from an orphanage in India nearly two years ago. The child was adopted from India and severely malnourished, the USA Today Network reported Thursday.
Wesley told investigators that it wasn't unusual for the girl to wake up in the middle of the night to eat something so that her weight would increase. That may explain why she was punished at 3 a.m., he said.
"Sherin did have a medical condition, and they have worked to get it under control", the lawyer said.