Rhys Jones was shot in a pub car park
The mother of Rhys Jones's killer has been jailed for three years for lying to detectives investigating the schoolboy's murder in Liverpool.
The judge told Janette Mercer, 49, she knew her son had told "a pack of lies".
She backed her son, Sean, 18, when he denied owning a silver bike caught on CCTV being used by the gunman.
Rhys, 11, was shot in Croxteth on 22 August 2007. Outside court Rhys's parents said what Mrs Mercer did to prolong their agony was "unforgivable".
Stephen and Melanie Jones said they felt they had "finally got justice" for their son.
Mercer had earlier admitted perverting the course of justice.
Francis and Marie Yates, the parents of Sean Mercer's co-accused James Yates, were also sentenced on Wednesday.
Rhys's parents added: "In our eyes Mrs Mercer and Mr and Mrs Yates have always been as guilty as their sons. As adults they should have known right from wrong.
Stephen Jones's statement following Janette Mercer's sentencing
"To intentionally cover up Rhys's murder and to protect a murderer and his accomplices and prolong our agony is unforgivable.
"As parents themselves they should have understood our pain but instead they chose to ignore it."
Marie Yates, 51, hindered the murder investigation by destroying a mobile phone Sim card belonging to her son which denied police vital evidence.
Francis Yates, 49, was with his wife when the card was set on fire and also suggested a false alibi to help Mercer cover his tracks.
The couple, from Dodman Road, Croxteth, pleaded guilty to perverting the course of justice and were sentenced to 18 months for destroying the Sim card.
'Mindless gang warfare'
The court heard evidence from a listening device placed in the Yates' home in which Mrs Yates said that Rhys's killer must have had "a lot of bottle".
"Oh my good God, brave isn't it?," she said.
Francis Yates was jailed for three years, to be served consecutively, for helping Mercer with a false alibi.
Judge Henry Globe QC said the shooting of Rhys Jones was the result of "mindless gang warfare" and had "saddened the lives of all decent people".
Janette Mercer backed her son and "told more lies"
To Mercer he said: Your son was a key suspect in the murder and you knew he had told a pack of lies.
"You backed him up and you told more lies."
Addressing the Yateses and Mercer, he said: "The complexity of the police investigation was such that nobody was able to be charged with any offence for many months.
"You wasted valuable police time and undermined the prospect of justice."
Sean Mercer, of Good Shepherd Close, Croxteth, was jailed for life in December for the murder of Rhys.
James Yates was one of the Croxteth Crew gang members who helped Mercer conceal the killing.
Yates, 20, was jailed for seven years for providing the gun which Mercer used to kill Rhys.