The son of murdered police accountant Curtis Cheng says he is relieved after the last extremist involved in his father’s murder was sentenced.

The fourth extremist involved in the murder, Mustafa Dirani, has been jailed for at least 21 years after being convicted for conspiring with others to prepare and plan a terrorist attack.

The 26-year-old helped source the gun used to murder police accountant Curtis Cheng outside police headquarters in Parramatta in 2015.

Alpha Cheng tells Ben Fordham his family has welcomed the decision.

“It is just a massive relief that this chapter has potentially come to a close.

“Someone who is of huge risk to society, that’s done such a terrible act, will be removed from society for a very, very, long time.”

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