28-year-old James Riley pleaded guilty to the offence....
He appeared at Manchester and Salford Magistrates Court yesterday (Monday 1 January)....
Just devastating....
The pair have been handed lengthy sentences after the "vile and predatory attack"....
The distressing incident happened when the man was on his way to work one ......
The teenager cannot be named for legal reasons....
"We cannot believe that he has died in such a violent and tragic way."...
A 22-year-old man has been arrested on suspicion of murder....
He wore a costume depicting Salman Abedi....