The gunman behind the cafe siege in Sydney had dropped off the Australian national security agency's watchlist, Prime Minister Tony Abbott said.
Mr Abbott said Iranian-born Man Haron Monis was on the organisation's watchlist in 2008 and 2009 but was later dropped from it.
Speaking to the media, Mr Abbott said: "I don't know why he dropped off the watch list in those days, I really don't."
He said answers were needed as to why Monis, who faced a string of charges including being an accessory to the murder of his ex-wife, had been out on bail and also possessed a gun licence.
Mr Abbott said: "We particularly need to know how someone with such a long record of violence and such a long record of mental instability was out on bail after his involvement in a particularly horrific crime,"
He added: "And we do need to know how he seemed to have fallen off our security agency's watchlist back in about 2009."
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"It was pretty loud, pretty frightening - like nothing I'd ever seen before ever," Greg Parker said.