A judge yesterday described a teenager accused of murdering his girlfriend's 11-month-old baby as “inadequate and irresponsible”.Judge Peter Jacobs also criticised the “totally aimless lifestyle” of the 17-year-old boy, who cannot be named for legal reasons.

A judge yesterday described a teenager accused of murdering his girlfriend's 11-month-old baby as “inadequate and irresponsible”.

Judge Peter Jacobs also criticised the “totally aimless lifestyle” of the 17-year-old boy, who cannot be named for legal reasons.

He was summing up in the Norwich Crown Court trial of the teenager, who denies murdering Ruby Spink on September 16 last year.

The child's mother, Laura Spink, has already admitted neglect.

She left Ruby alone with her boyfriend, who was not the child's father, in her room at a Yarmouth hostel. When she returned a few minutes later, she found the little girl lifeless and floppy.

The youth initially claimed Ruby had choked on some cake he had fed her, but later changed his story, saying she had hit her head by accident on a wall as he twirled her round to cheer her up.

The court heard from an expert witness who said Ruby's head injuries were similar to those commonly caused by a 30mph road crash or a fall from a first-floor window.

Judge Jacobs told the jury: “It's clear to all of us that her short life was not a particularly happy one. The care she received was wholly inadequate and her short life ended in a particularly dreadful way.”

Referring to Spink and her boyfriend, he said: “Both were plainly inadequate individuals and totally irresponsible individuals”.

He described the youth's lifestyle as “totally aimless” but told the jury: “That's not the issue.”

Telling the jury they should make allowances for the youth's age, immaturity and inexperience, he said: “That's not the same as sympathy. It's a balanced approach to the evidence.

“The prosecution must prove that the defendant somehow deliberately struck Ruby's head against a hard, flat surface such as a wall. The defence case is that this was an accident caused by play; turning around quickly, or 'twizzling' in an attempt to cheer her up.”

The jury was considering its verdict overnight.