Thomas Cashman will reportedly be kept in isolation for his own safety after mobsters put a £250k hit on him.
Cashman, 34, has been jailed for life with a minimum of 42 years for the murder of nine-year-old Olivia Pratt-Korbel.
He is said to be "public enemy number one" inside HMP Manchester. He faces time in isolation to keep him away from those wanting to harm him, The Sun newspaper is reporting.
"Cashman will be in isolation for a period of time for his own sake," a source told the newspaper.
"It'll be easier for all involved. There's fears he will grass to get an easier life in prison as an informer. And also there's people out for revenge. Not least Kirk Bradley - who is influential - and has a lot of friends within the prison community.
"Cashman is a real target. The £250,000 bounty will entice people."
A Ministry of Justice (MoJ) source told the PA news agency: "Olivia Pratt-Korbel and her family weren't able to hide from Thomas Cashman's crime - so he shouldn't be able to hide from justice.
"This is exactly why the Deputy Prime Minister is committed to changing the law so that offenders are forced to face the consequences of their actions."
On Monday, he failed to appear in the dock for his sentencing, which saw him handed a life sentence with a minimum term of 42 years.
The jury was told he lay in wait for Joseph Nee on Kingsheath Avenue, armed with two guns, and then chased him, firing three shots in the street, when Nee left a house shortly before 10pm. Nee ran towards the open door of Olivia's home after her mother went out to see what the noise was, the court heard.
The bullet which killed Olivia was fired through the front door, hitting the wrist of Ms Korbel, who was trying to hold the door shut, before striking Olivia in the chest. A woman who had a fling with Cashman told the jury he came to her house after the shooting, where he changed his clothes and she heard him say he had "done Joey".
During his evidence, Cashman admitted being a "high-level" cannabis dealer. But the father of two told the court: "I'm not a killer, I'm a dad."
The jury took more than nine hours to find Cashman guilty of Olivia's murder, the attempted murder of Nee, the wounding with intent of Ms Korbel and two counts of possession of a firearm with intent to endanger life.
