The mother of a Richardson girl found dead last month in a culvert was arrested Thursday because police say she and her husband left the 3-year-old home alone the night before she was reported missing.

Sherin Mathews

Sini Mathews and husband Wesley Mathews, who was arrested last month, went out with their biological daughter Oct. 6, leaving Sherin Mathews because she refused to drink her milk, police said.

The 35-year-old mother was arrested about 3 p.m. Thursday after her attorney took her to the Richardson police station.

Sini Mathews 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.

"This all stems from this ongoing investigation with Sherin. It's sort of a culmination of everything we've got so far," police Sgt. Kevin Perlich said. "It was our decision that now was an appropriate time to make an arrest."

Sini Mathews

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 Oct. 23, Wesley Mathews said that he and his wife had left Sherin, whom the couple had adopted from India, 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 Mathews

Wesley Mathews 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 they returned home an hour and a half later. An affidavit said the girl was in the kitchen where they left her.

Wesley Mathews told police that at some point later that night or early the next morning, he helped Sherin with her milk, but she choked and stopped breathing, police said.

"He doesn’t get help. He doesn’t seek assistance," Perlich said.

Sini Mathews was reportedly asleep and unaware of what was going on.

Wesley Mathews had originally provided police with an alternate account. He first called police at 8 a.m. Oct. 7 to report that Sherin had gone missing after he sent her out to an alley near their home about 3 a.m. because she was not drinking the milk.

When he spoke to police again Oct. 23, his story had changed to include that he had "physically assisted" the girl with the milk after leaving her home when the rest of the family left for dinner. He removed her body from the home after that, according to an affidavit.

Police continue to investigate Sherin's death, and evidence is being evaluated. The Dallas County medical examiner has not yet ruled on the cause of death.

Sini Mathews, a nurse who works at Children's Medical Center Dallas, could face different or additional charges, Perlich said.

Her attorneys, Mitchell R. Nolte and Gregg Gibbs, said they learned Thursday morning that an arrest warrant had been issued.

"The police were professional and courteous and allowed us to bring Mrs. Mathews to the Police Department and surrender herself into custody," they said in a written statement.

1 / 9A poster board left for people to send Sherin Mathews a message was available for people sign at the vigil held in Richardson on Oct. 20, 2017. The vigil was held in an alley by a tree near her parents' house.(Ron Baselice / Staff Photographer) 2 / 9Sini Mathews, foreground, mother of Sherin Mathews, leaves Judge Cheryl Lee Shannons courtroom where she learned that her biological child, a 4-year-old girl, will remain in foster care for another three weeks while Wesley Mathews looks for a civil attorney. The custody hearing was held at the Henry Wade Juvenile Justice Building on Monday, November 13, 2017. Wesley and Sini Mathews first appeared in court on Oct. 23 to try to regain custody of the biological daughter who was taken into Child Protective Services custody after Sherin was reported missing Oct. 7, 2017. The Judge has scheduled a new hearing for November 29, 2017. (David Woo/The Dallas Morning News)(David Woo / Staff Photographer) 3 / 9Wesley Mathews, right, adoptive father of Sherin Mathews, was arrested and charged with Injury to a Child arrives at the Lew Sterrett Justice Center on Wednesday, October 25, 2017 in Dallas. He was transferred from the Richardson, Texas jail and his bond has been set at $1,000,000. He was arrested on Oct. 23, 2017 after offering a new account of how his daughter went missing two weeks earlier. (David Woo/The Dallas Morning News)(David Woo / Staff Photographer) 4 / 9A stretcher is moved from the location where the location where the body of a young child was found on Sunday, October 22, 2017 at the corner of E Spring Valley Road and S Bowser Road in Richardson, Texas. It has not been confirmed if the body was missing three-year-old Sherin Mathews. Mathews was last seen at 3 a.m. on Saturday, October 7, 2017, when her father, Wesley Mathews told police he took her outside to stand by a tree about 100 feet from their home, as a punishment for not drinking her milk. He was arrested on a charge of abandoning or endangering a child, and was later released from custody after posting bail. (Ashley Landis/The Dallas Morning News)(Ashley Landis / Staff Photographer) 5 / 9FBI investigators get dressed in protective suits as they work a crime scene where the body of a child was found near the home of missing girl Sherin Mathews, Sunday, Oct. 22, 2017. Ben Torres/Special Contributor(Ben Torres / Special Contributor) 6 / 9A growing memorial in the area where the body of a small child was found Sunday morning during the search for a missing 3-year-old girl, Richardson police announced Sunday. Police have not yet confirmed that the body is that of Sherin Mathews, who has been missing since Oct. 7. Photo taken on Oct. 23, 2017 in Richardson, Texas. (Nathan Hunsinger/The Dallas Morning News)(Nathan Hunsinger / Staff Photographer) 7 / 9FBI investigates search a grass area near a storm drain after a body of a child was found near the home of Sherin Mathews, Sunday, Oct. 22, 2017. Ben Torres/Special Contributor(Ben Torres / Special Contributor) 8 / 9People gather at a memorial for missing three-year-old Sherin Mathews on Sunday, October 22, 2017 at a tree behind her home at the 900 block of Sunningdale in Richardson, Texas. Police found the remains of a young child at 11 a.m., but have not confirmed that it is Mathews. Sherin Mathews was last seen at 3 a.m. on Saturday, October 7, 2017, when her father, Wesley Mathews told police he took her outside to stand by a tree, pictured, about 100 feet from their home, as a punishment for not drinking her milk. He was arrested on a charge of abandoning or endangering a child, and was later released from custody after posting bail. (Ashley Landis/The Dallas Morning News)(Ashley Landis / Staff Photographer) 9 / 9Members of an FBI evidence response team work at the family home of Sherin Mathews in the 900 block Sunningdale, on Tuesday, Oct. 10, 2017, in Richardson, Texas. Authorities on Tuesday evening searched the Richardson home of a 3-year-old girl who has been missing since Saturday when her father reportedly sent her outside as punishment for not drinking her milk.(Smiley N. Pool/The Dallas Morning News)(Smiley N. Pool / Staff Photographer)

Authorities searching less than a mile from the Mathewses' home Oct. 22 found the body of a small child later identified as Sherin in a culvert. Her body was identified two days later.

Wesley Mathews, 37, remains in the Dallas County Jail on a charge of causing serious bodily injury to a child. Bail has been set at $1 million.

Sini Mathews appeared before a family court judge 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 extended family. Police had previously given an incorrect age for the girl, but on Thursday said she is 3.

The judge decided to delay the custody proceedings because of "aggravated circumstances" in the case, though the court did not address what the circumstances are. The hearing has been reset for Nov. 29.

The search for Sherin Mathews

Richardson police and other agencies scoured the city for 3-year-old Sherin Mathews after her disappearance was reported Oct. 7. Her body was found Oct. 22.

Oct. 7

3 a.m.: Sherin Mathews is reportedly last seen by her father, who said he put her in an alley near the family's home because she refused to drink her milk. Wesley Mathews said the 3-year-old was gone when he went to check on her 15 minutes later. The father later told police he did laundry and went inside to wait for her to return.

4 to 5 a.m.: Police said the Mathews family's maroon Acura was gone at that time and asked people in the area to check surveillance videos for the SUV.

8 a.m.: Police are called about Sherin's disappearance.

2:10 p.m.: An Amber Alert is issued for Sherin.

Evening: Wesley Mathews is arrested and charged with endangering a child.

Oct. 8

2:30 p.m.: The Amber Alert is discontinued because of a lack of tips.

Evening: Wesley Mathews is released from jail after posting bail.

Oct. 9

Wesley and Sini Mathews' 3-year-old biological daughter is removed from the home by Child Protective Services.

Oct. 10

7 p.m.: Richardson police and an FBI team enter the family's house with a search warrant and remove many items, including the washing machine and dryer, contents of a vacuum and electronics.

Oct. 11

2 p.m.: Kent Starr, the attorney for Sini Mathews, speaks to reporters outside the family's home, stressing that she did not face any charges and that the husband and wife love Sherin.

Oct. 22

11 a.m.: Officials searching less than a mile from Sherin's home discover the body of a small child in a culvert. Police are awaiting positive identification.

Oct. 23

A Dallas County judge postpones a custody hearing involving the Mathewses' 3-year-old daughter, leaving the girl in foster care for another three weeks. After the court appearance, Wesley Mathews and his attorney go to police and the father offers a new version of events. He is arrested.

Oct. 24

The body found in the culvert is identified as Sherin.

Oct. 31

Sherin is buried in a private ceremony at an undisclosed location.

Nov. 13

A family court judge decides to reset the custody hearing for Sherin's sister to Nov. 29, citing "aggravated circumstances.

Nov. 16

Sini Mathews is arrested and charged with abandoning or endangering a child.