A Christian hip hop producer convicted of the murder of a seven-year-old, whose fatal injuries he tried to blame on a fall from a pogo stick, should be jailed for life, a court has heard.

Kodi Maybir's "horrific, horrendous, inhuman" treatment of the boy, who died at Maybir's Oatley music studio in Sydney's south in May 2013, was in the worst category of offences, crown prosecutor Chris Maxwell told the NSW Supreme Court on Friday.

Justice Robert Allan Hulme said it was still unclear exactly how the boy had died, as Maybir had repeatedly lied to the court and had given four different versions of what caused the boy's fatal injuries.

"They have been pretty poor attempts on each occasion," Justice Hulme told the court.