A jury at Manchester Crown Court heard that Violet Mullen was punched, slapped and pinched several times during the three weeks before her death in January. When he punched the child in the stomach internal organs were torn, which resulted in her death.
Gary Alcock, 28, must serve at least 21 years before being eligible for parole.
The child’s 22-year-old mother, Claire Flanagan, was cleared of murder, but convicted of causing or allowing her daughter's death by ignoring the obvious signs of abuse – including blood stains. She was sentenced to five years in jail.
"You could have sought medical help, you could have involved social services, you could have asked him to leave, but any of those options would have put at risk your relationship, which you, at the time, priced far more highly than your relationship and love for Violet,” The Guardian
quoted Judge Clement Goldstone QC as telling Flanagan.
"As a mother you failed her miserably. That is something you will have to live with for the rest of your life."
In January Alcock, annoyed because the sick child’s cries were disrupting his Xbox game, struck Violet in the stomach so hard that it tore her internal organs. He then put her in her cot to wait for her mother to return home.
reported that he later called an ambulance and told the operator that the girl had cold, blue lips and seemed “spaced out.”
When paramedics arrived they found Violet was not breathing and covered in bruises. She died 45 minutes after arriving at hospital.
A postmortem found that Violet died from internal bleeding after suffering 35 injuries including bruises, fractured ribs and brain damage.
"Yours was a truly horrific and cruel crime of murder in which you have shown absolutely no remorse or shame," Judge Goldstone told Alcock.
"You fractured two of her ribs either by squeezing or gripping her so tight that they snapped.
"You caused injuries to her brain, face, arms and legs with a combination of punches, slaps and, bordering on the sadistic, pinches.
"This was the way you chose to cope with a demanding little girl who demanded your attention and interrupted your time-consuming hobby of playing computer games."
Alcock, who had been convicted of assaulting a former girlfriend, moved in with Flanagan 48 hours after they began dating.