Julissa Thaler, who is accused by law enforcement of killing her 6-year-old son Eli Hart shortly after regaining parental custody last spring, has been indicted on charges of first-degree murder.

Thaler, who is jailed in lieu of $2 million bail in Hennepin County, was already charged with second-degree murder. The first-degree count, which carries a mandatory life sentence without the possibility of release if Thaler is convicted, was added on Friday, according to court records.

"The only surprise in this indictment is how long its took the County Attorney's Office to get one," Thaler's public defender, Bryan Leary, said. He said his defense of Thaler "will point out the reasonable doubts that lurk in the evidence."

Thaler was offered a plea agreement last week on the second-degree charge, which would have meant agreeing to a 40-year sentence, Leary said. She did not act on the offer before Friday's indictment.

Eli Hart's body was found in the trunk of Thaler's car in Mound in May. He was killed just 10 days after Thaler was reawarded custody by a Dakota County judge.

Eli's father, Tory Hart, was attempting to regain custody of his son at the time of the boy's death. In August, he also filed suit against Dakota County and three county employees. The suit claimed that officials ignored signs that Eli would not be safe in Thaler's care, including Thaler's alleged history of substance abuse and hospitalization for mental illness.

Hart's attorney in that suit, Joshua Tuchscherer, did not immediately respond to a phone message requesting comment.

A trial in the murder case is scheduled for Jan. 30, according to court records.