Sini Ann Mathews and husband Wesley Mathews, who was arrested last month, went out for dinner with their 3-year-old biological daughter October 6, the night before she was reported missing by her adoptive father.
The couple from Kerala, allegedly left Sherin alone in the kitchen because she refused to drink her milk, police in Richardson, Texas said yesterday.
The 35-year-old mother was arrested yesterday after her attorney took her to the Richardson police station.
She is being held in the Richardson jail on a charge of abandoning or endangering a child, a state jail felony. Bail has been set at $250,000, police said.
Sini, a nurse who works at Children's Medical Center Dallas, could face different or additional charges, Perlich said on the case which has been widely reported in the international media.
Sini appeared before a family court judge on Monday to attempt to regain custody of her biological daughter, who is expected to be moved at some point out of foster care to live with an extended family member.
A state jail felony in Texas is an offense that is punishable by confinement in a state jail facility from six months up to two years.
"This all stems from this ongoing investigation with Sherin. It's sort of a culmination of everything we've got so far," police Sergeant Kevin Perlich said.
"It was our decision that now was an appropriate time to make an arrest," the Dallas Morning Post quoted him as saying.
Detectives determined Wesley and Sini Mathews went to a restaurant in Garland with their 3-year-old biological daughter, leaving Sherin home alone, placing her in "imminent danger of death, bodily injury, or physical or mental impairment," according to the arrest warrant affidavit.
Cellphone records show both parents' phones were at the restaurant that evening. A receipt showed only one child's meal had been purchased, the affidavit stated. The waiter also confirmed that only one child was at the meal.
In an interview with detectives October 23, Wesley, the 37-year-old foster father, said that he and his wife had left Sherin, alone while the rest of the family went to eat dinner.
He said he became impatient when Sherin refused to drink her milk and went to dinner without her, the affidavit stated.
Wesley told detectives that he asked his wife to go with him and Sherin's sister and Sini did so without being coerced, police documents state.
Police said they have not determined whether Sherin was alive when the couple returned home an hour and a half later, the Dallas Morning News reported.
An affidavit said the toddler was in the kitchen where they left her.
"The Dallas County Medical Examiner's Office is continuing to work on determining the cause of death. Those results will be made available when complete," Richardson Police said in a Facebook post.
Wesley, who has since been charged in connection with Sherin's death, remains in the Dallas County Jail on a charge of injury to a child. Bail has been set at USD 1 million. The crime is punishable with up to 99 years in prison.
Wesley had initially said he sent Sherin outside to an alley near their house about 3 am because she refused to drink her milk.
He later changed his story and to say he "physically assisted" Sherin with her milk, and admitted to removing her body from the home after she choked and stopped breathing, according to an arrestwarrant affidavit.
Authorities launched a massive search and a cadavour dog found the body of a small child in a culvert on October 22. The body was later identified as that of Sherin.
Sherin's death prompted External Affairs Minister Sushma Swaraj to ask the Indian Embassy in the USto be actively involved in the case and keep her informed. She also sought a probe into the adoption process of Sherin, who was adopted by the Indian-American couple last year from Bihar.
Following Sherin's case, India decided that passports to adopted children will be issued only with prior clearance by the Ministry of Women and Child Development.