Now, Autumn’s memory remains everywhere in the apartment. Her rain boots are next to the door. Her bunny slippers are a few feet away. Her name is monogrammed in green letters on a bulging toy box sitting near a toy stove and a bright pink vanity.

“She was too perfect for this world,” Ms. Coleman, 36, said one recent evening.

In interviews, Ms. Coleman could barely talk about Autumn’s death without lacing every sentence with an expletive. She was angry and numb.

Family Court is full of emotional quicksand. Judges in custody disputes are charged with balancing the best interests of children with the rights of parents while trying to sort through allegations made by desperate or angry ex-partners.

But Ms. Coleman said she had tried to tell the court that her daughter was in danger. No one would listen.

‘He’s freaking me out’

Ms. Coleman was outside with friends when she met Mr. Pereira, who was walking by. After they had been together about a year, Ms. Coleman became pregnant. Her sister, Nicole, planned the baby shower, an elaborate affair in an event hall bathed in pink-colored lights.

Mr. Pereira proposed to Ms. Coleman at the party, but the celebration turned mournful when her father had a fatal heart attack that night. His death put wedding plans on indefinite hold and strained the couple, who were already having problems. They could not even agree on Autumn’s name. Mr. Pereira called the girl Zoey and gave her his last name.

Years of tension escalated inside Mr. Pereira’s car on March 13, when Ms. Coleman returned the engagement ring. Two days later, Ms. Coleman’s mother, Denise, was alarmed to see that he was wearing the ring on his pinkie finger when he picked Autumn up for a visit.