Robinson was described as the on-again, off-again boyfriend of Jenkins-Minus. He is being held without bail.
"Dejah was found in the house that he was living in alone, in his bedroom, which was locked when any witness or the police came to that location," a prosecutor said in court.
Officers found Jenkins-Minus suffering from a fractured neck and with more than 58 stab wounds.
"Further investigation revealed that there had been social media posts by the defendant, questioning whether he was the father of the child, questioning whether he should have a DNA test, and also stating also stating that he was mad a Dejah and I would suggest providing motive," the prosecutor continued.
Police went to a Lowell home on Friday for a well-being check on her and her 2-month-old daughter. The baby was not hurt.
LaToya Minus, Dejah's mother, told WBZ-TV over the weekend her daughter was a "very uplifting young lady."
"I'm lost, I'm hurt, I'm numb. I'm angry and I want justice for my baby and my grandbaby," she said.
Dejah's mother had called police for the well-being check.
A probable cause hearing has been scheduled for December 30.
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