Immigration looking into shooter's history

The Immigration Department is looking into the circumstances in which the family of the Parramatta teenage shooter came to Australia, Peter Dutton says.

Immigration officials are investigating how the family of the Parramatta shooter came to Australia. (AAP)

Immigration officials are investigating the circumstances in which the family of a 15-year-old who shot dead a NSW Police employee came to Australia.

It appears Farhad Khalil Mohammad Jabar's family moved to Australia ahead of him, Immigration Minister Peter Dutton told 2GB radio on Thursday.

But Mr Dutton said he had not seen any information about Jabar's sister travelling to Turkey a day before last Friday's attack.