Shwe Htoo held her composure for as long as possible Thursday morning as she recounted how she fed milk laced with sugar, sleep medication and bedbug poison to her 1-month-old son one night and then drank the mixture herself.

She testified in Ramsey County District Court that when they both woke up the next morning — Nov. 18, 2015 — she was desperate to end both of their lives: "I covered his nose with my hand and he couldn't breathe, and then — "

Htoo buried her face in both hands, leaned forward in her chair and broke into sobs.

"And then he just died," she testified.

The admission came during a hearing at which Htoo, 23, pleaded guilty to one count of first-degree manslaughter for killing Michael Kyaw Htoo.

Court records indicate that at the time, she was suffering from postpartum depression, which can overwhelm new mothers with depression, anxiety and mournful feelings.

The original count of second-degree murder will be dismissed as part of her plea deal. Htoo also agreed to a prison term of between 12½ years and 15 years, an upward departure from state guidelines that would have otherwise called for about six to 8½ years.

The higher sentence is based on aggravating factors: The baby was especially vulnerable because of his age, Htoo acted with "particular cruelty" and her actions were carried out with a "high degree of planning, preparation and concealment."

Htoo could be deported after she serves her prison time in Minnesota.

Under questioning by Assistant Ramsey County Attorney Hao Nguyen, Htoo admitted that she first tried to poison her son and herself on the night of Nov. 17. The baby only drank a little of the mixture, she said through a translator, but she drank more and blacked out.

Htoo, who is Karen, testified that she was unhappy in her cultural marriage to the baby's father, who worked at a turkey processing plant in Willmar, Minn., and was often away for extended periods.

Htoo testified she didn't know how to drive, but said that after she killed her son, she drove to Como Regional Park with his body strapped in a car seat.

"I was looking for a place to die," Htoo testified. "I was looking for a lot of places to crash myself and kill myself."

Htoo told the court that she drove into a rock. The criminal complaint filed against her said she drove into a light pole.

Htoo's cultural husband, who attended the hearing, said afterward that he was unable to make a statement because he did not speak English. Ken Severson, a family friend, spoke on their behalf.

"I just know how much she loved Michael and how desperate she was," said Severson, who came to know the family through his volunteer work. "Does [the postpartum depression] excuse the crime? Probably not. But does it explain it?"

Severson said that Htoo was born in Burma, spent several years in a Thai refugee camp and has been in the United States about two years.

Htoo underwent mental health evaluation, and in December 2015 was found incompetent to stand trial. That decision was reversed last March. She is to be sentenced on March 22.

Chao Xiong • 612-270-4708

Twitter: @ChaoStrib