A New London judge sentenced Michael A. Rios to 14 years in prison Monday in connection with the shaking death of his girlfriend’s 13-month-old daughter, Madison Alexa Reid, in May of 2013 in Norwich.

Rios, 23, had pleaded guilty in July to first-degree manslaughter.

The victim’s relatives, many of them dressed in neon pink T-shirts that said “Madison Matters,” held up photographs depicting the bubbly toddler’s short life during an emotional sentencing hearing in Superior Court.

Under a plea agreement worked out between prosecutor Theresa Anne Ferryman and defense attorney Christopher L. Morano, the defense had a right to argue for a reduced sentence. But after hearing impassioned pleas from both sides, Judge Hillary B. Strackbein imposed the entire sentence — 20 years in prison, suspended after 14 years served followed by five years probation.

“From what I calculate, you could be less than 36 years old when you are released, and this child will have nothing,” Strackbein told Rios.

His family members had pleaded to the judge for leniency, describing Rios as a gentle soul who loved Elizabeth Reid and wanted to be a father to her daughter. Rios, who had graduated from Norwich Tech and attended Three Rivers Community Technical College, had enlisted in the Air Force National Guard and was to begin basic training five days after Madison died. The Rios family characterized the child’s death as accidental.

The child’s survivors, however, emphasized the serious injuries she suffered and hinted medical records contained disturbing evidence of another crime with which Rios had not been charged.

“All this being said, we feel that any reduction in Rios’ sentence, by so much as a single day, would be an affront to the memory of an innocent murdered child and a harsh slap in the face to the survivors and all those who have been affected by crimes such as this,” said Madison’s step-grandfather, Lawrence E. Berkman, a Rhode Island dentist.

Ferryman said the state reviewed all the evidence and concluded there was no basis for any additional charge.

Rios had been dating Madison’s mother, Elizabeth Reid, for a few months and had agreed to take care of the toddler at her Norwich home and drop her off at day care after Reid left for work on May 2, 2013. The child was unconscious and bleeding from the brain when he took her that day to The William W. Backus Hospital. She was flown to the Connecticut Children’s Medical Center, where she underwent emergency surgery, but she succumbed to her injuries during the early-morning hours of May 3. She died in her mother’s arms.

Madison suffered a subdural hematoma and retinal hemorrhaging, and the state Office of the Chief Medical Examiner ruled her death a homicide.

Rios told police that Madison became unresponsive after falling from a bed and he “shook her very hard” to get her to respond. Rios had no prior criminal record.

His sentencing complete, Rios, who had been free on a $100,000 bond, was taken into custody Monday while his family members, many of them in tears, filed out of the courtroom.

The child’s family members, gathered in the hallway outside the courthouse, said they had hoped for a lengthier prison term, but were relieved that Strackbein had not reduced the sentence.

“I’m so glad the judge understood that Madison Alexa Reid matters in this world,” said her paternal grandmother, Colleen Reid.

k.florin@theday.com

Twitter: @KFLORIN