Court documents show that police raided the home of the former intelligence officer Cameron Jon Gill in September because they suspected he was the source of Annika Smethurst’s story revealing plans to expand spying powers.

The special case book in Smethurst’s high court appeal and the attached warrant for the raid on Gill’s home both name Gill as the staff member of the Australian Signals Directorate who police suspect of having communicated classified information to Smethurst.

News Corp has said that Smethurst has never revealed the source’s identity, even to her employer. Guardian Australia does not suggest that Gill’s inclusion in the case book – a statement of facts and questions of law agreed by Smethurst and the Australian federal police – proves he is the source.

But the documents confirm that the raid on Gill’s home was directly linked to the raid on Smethurst’s home in June that unleashed a fierce campaign by media companies for greater press freedom. Gill is also named in both warrants for the Smethurst raids.

In August the home affairs department secretary, Michael Pezzullo, said police were “closing in” on the suspect who he said, subject to proper judicial processes, should “go to jail”.

Smethurst and News Corp are locked in a high court battle to force police to destroy or refrain from using material seized in the June raid.

The Australian federal police have undertaken not to use the material, but its lawyers have told the court this undertaking will expire at the conclusion of her case challenging the validity of the warrant, and the information “may well be important” for a potential future prosecution.

The court has heard this includes potential referrals to the commonwealth director of public prosecutions to consider laying charges against Smethurst’s source for a breach of the Intelligence Services Act, and Smethurst for the Sunday Telegraph article that reproduced part of the classified document.

Police have never ruled out referring a brief of evidence for possible charges against Smethurst, although the attorney general would have to consent to that.

At Wednesday’s hearing Smethurst’s counsel, Stephen Lloyd, said the solicitor general, Stephen Donaghue, had hinted that a police referral to the commonwealth director of public prosecutions was “proximate” and had invited the court to infer that the only reason it had not yet occurred was that they had been unable to examine material seized. Lloyd urged the court not to refuse an injunction because of the mere possibility of charges.

The warrant for the raid on Gill’s home authorised police to look for emails, encrypted messages, notes and the leaked document titled ASD as a Statutory Agency – Further Amendments to the Intelligence Services Act 2001 provided they related to Smethurst, the Sunday Telegraph, ASD, the departments of defence and home affairs, or two other persons or entities whose names are redacted.

Police were entitled to search for materials provided there were reasonable grounds for suspecting they would afford evidence relating to the following alleged offence:

“Between 1 February 2018 and 29 April 2018, Cameron Jon Gill being a staff member of the [ASD] communicated [ASD] information to Annika Claire Smethurst contrary to section 40 of the Intelligence Services Act 2001.”

The special case book notes the raids in June were conducted under two warrants: the first issued on 31 May authorising searches of her premises and a vehicle; the second on 3 June authorising a different AFP officer to search the premises.

Referring to the publication of the Sunday Telegraph article, both warrants said: “On the 29 April 2018, Annika Smethurst and the Sunday Telegraph communicated a document or article to a person, that was not in the interest of the commonwealth, and permitted that person to have access to the document, contrary to section 79(3) of the Crimes Act 1914, Official Secrets.

“On 4 September 2019, members of the AFP purportedly executed a search warrant …at the premises of Mr Cameron Gill, being the person (other than Ms Smethurst) who was named in the second condition of the first warrant and the second warrant,” the case book said.

A News Corp spokesman told Guardian Australia it would be “inaccurate to report speculation [that Gill was the source] as fact”.

“Annika has never revealed her source publicly, privately or to her employer, and we’re not going to ask her.

“Any further comment would be inappropriate as the matter is before the court.”

At the time of the September raid on Gill’s home, News Corp’s head of government affairs, Campbell Reid, said: “We have always said the AFP raids on journalists were not intended to intimidate journalists but the people who have the courage to talk to journalists. Today we are seeing that process of intimidation continue.”

The court adjourned on Wednesday, to return on a date yet to be fixed.

On Tuesday the court urged Smethurst’s lawyers to clarify the basis for an order to destroy documents and consider pleading breach of confidence or seeking an order to prevent the use of material copied from her phone rather than its destruction.

Lloyd told the court that the issue with pleading breach of confidence was “the need to disclose the material that we seek to keep private”.

Chief justice Susan Kiefel asked Lloyd to confine submissions to the validity of the warrant rather than elaborate on claims the section 79(3) offence breached the implied freedom of political communication.