It comes amid warnings that public officials, including parliamentarians, are facing an unprecedented level of extremism and violent threats in Australia.
On Tuesday, Australian Federal Police and NSW Police released excerpts of anonymous letters sent by a person going by the aliases "Scorpio" and "Bullit".
They are among more than 100 notes sent to parliamentarians, religious groups and community leaders from 2015 to 2026 and seized by police.
Some constitute threatening or harassing behaviour, investigators said.
The author's identity remains a mystery but he is believed to be a man of Caucasian appearance aged in his 60s.
Police have released excerpts of the letters in the hopes the public can help in identifying the author by their distinctive handwriting style.
Among the clippings is a menacing smiley face with what appear to be impressions left by bullet casings for eyes.
The priority of police was to prevent any escalation into behaviour that could endanger the community, AFP Superintendent Nathan Robertson said.
''People in public life deserve to go about their jobs or careers without being subject to harassment or threats,'' he said.
Police did not reveal which politicians or community leaders were targeted with the letters.
But extremist expert and Deakin University associate professor Josh Roose said threats against public figures were rising across the board.
''The scale of the material that I'm seeing online is unprecedented,'' he told AAP.
Politicians, law enforcement officials and religious groups were all facing rising threats from disaffected individuals who spend a lot of time online.
While Australia has not experienced the same level of political violence seen in the US, for example, Assoc Prof Roose said similar trends were developing in the digital realm.
''What we're seeing is men, in particular, who are highly politically motivated, fixating on individual politicians,'' he said.
''They then target them for stalking, harassment and doxxing, where they attempt to find where they live and share those details.''
In the 2024/25 financial year, the AFP received 951 reports of violent threats against federal politicians, nearly doubling from the 555 reports received in 2021/22.
Assoc Prof Roose said online offenders were often middle-aged men who felt left behind by society.
''We see them, on the one hand, attracted to … anti-government extremist ideologies, but also anti-women and misogynistic material and ideologies,'' he said.
They tended to focus on politicians who appeared to embody their issues with society, with cost-of-living and migration key flash points, Assoc Prof Roose added.
On Friday, a Western Australian court sentenced William James King to seven months in prison for social media threats to kill Prime Minister Anthony Albanese and NSW Premier Chris Minns.
"I'll assassinate you and Albo, and the country will be a better place," he wrote in a direct message to Mr Minns' Instagram account in January.
His lawyer argued the 20-year-old had been reading political articles and online comments and had been triggered by housing and immigration issues.
King's sentence was conditionally suspended for 12 months and his lawyer argued he had no intent to make good on the threat.
Two days earlier, ASIO director-general Mike Burgess used his annual threat assessment to warn about the "acute concern" of politically motivated violence.
These involve violent acts or threats intended or likely to achieve a political objective, ranging from vandalising an electoral office to a terror attack.
He insisted the likelihood of such incidents was higher than the current threat level of "probable" suggested but not specific enough to reach the "expected" threshold.
The spy chief echoed calls by Mr Albanese to lower the temperature of political discourse after the 2025 Bondi terror attack.
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