When these days, kidnappers ring with the ransom demand, the nearby police quickly use electronic triangulation to work out where the call is coming from – to an accuracy of a few metres. It might take the goodies a minute or two to alert the telecommunications companies that they need such data, but those who rely on old TV drama, by which one seems to need to keep the villain on the phone for a few minutes until the postmistress clicks the pieces into place, are well out of date.

If, moreover, police (or, presumably counter-espionage folk) subsequently find the number of the phone they believe the villain might have been using, they use the "metadata" to confirm that particular calls were made, and establish, in an admissible way, exactly where the telephone was at the time the call was made. Indeed a villain carrying her own phone around in her pocket or handbag is handing to investigators, once caught, a log of her movements.

It's best, I gather, to switch your phone off. While it is on – it may be that while there is any sort of potential electric current – the phone is probably sending "here I am" signals and other metadata to a series of satellites, and, if the cops are on to it, they can, apparently, readily transfer such information to a Google map in their vehicle so that they can follow at a discrete distance with the baddies realising they are being followed. Indeed, it is said that there is technology by which an apparently off telephone can be transmitting the conversations, perhaps images, within range of the phone.

One can, of course, leave the phone at home. Or if one seriously wants to mislead the constabulary, lend it to someone else, remove the battery, or stow it on a car, bus or truck leaving town. In The Wire, the drug gang bought pay-as-you-go mobile telephones by the score and discarded them in short time.

I do not know these things as a fact, in the movies such techniques succeed in distracting police, or securing the privacy of some transactions, at least for a while. A film or a television show would not lie, even if it might convey a misleading impression about how readily available such technology is to an ordinary police investigator, or how seamlessly the arrangements with the telecommunication systems work.

I gather that the technology improves all of the time – and is now probably light years ahead of my understanding. But the essential capacity to closely monitor electronic communications, including email has been around for quite a while. A major external review of the safety of the conviction of a man for the assassination of an Australian politician in 1994 had police tendering evidence of the alleged murderer's telephone "footprints", as it were, with the suggestion that these were incompatible with his claimed alibi.

My grandmother used to say that beginning of wisdom was not trusting a friendly policeman. I have always warned impressionable journalists here that they never readily succumb to the honeyed invitation of an investigator for one's phone numbers, including mobile numbers, "just in case I need to get back to you". Such are fed into police data bases and used for cross-matching during leak investigations. Thousands of calls from, say, a government department, (as well as the home and mobile numbers of officers) will be checked for matches with numbers of the gutter press, Russian Embassy, or perhaps the local branch of Islamic State.

But it does seem that there are some limits to what law enforcement technical expertise can achieve. Especially if it is the police themselves whose conduct is in question.

When John Passant, well known left-wing ratbag, activist and taxation expert, republished on his website some tendentious material about a Melbourne demonstration, "I received a torrent of abuse in the comments section of the article."

"One respondent threatened to kill me, " he wrote recently. "They[sic] wrote: 'They should put a bullet in you, for the good of everyone else.' Another said... 'I hope you drown the next time you do one of your little aquarobics classes friend.' "

Another abusive respondent used a spelled-out obscene pseudonym DUC, from two separate computer addresses. As it happened, one IP address that DUC was using was the Victoria Police Centre at 637 Flinders Street, Melbourne.

"DUC also used a fake email address with the words 'german sausage' (not visible to readers) in it. Another post also used the same fake email address but from a different IP (presumably home) address. It would be reasonable, based on the use of the same fake and not public email, to assume that the two are the same person."

Passant complained in a number of directions. The ACT Attorney-General, Simon Corbell suggested that Passant report the threat to the ACT AFP, and also that he complain to the Victoria Police conduct unit. The AFP was not much interested, pointing out that since Passant had not been killed, it was likely that the person in question was but a troll. No doubt the ACT AFP was too busy at the time investigating speeding offences by little old ladies, or suggestions, since retracted after they had done their damage, that a dead man had been threatening the life of the prime minister.

Passant says there was a long dead silence for months from the Victoria Police, but that after he agitated the matter, an officer confirmed the email had come from police HQ. Alas, the police were not able to establish from which computer it had come. They did not much seem inclined to try either.

I should not be in the least surprised if a more diligent investigation had been able to take the matter further, but even less surprised at the reluctance to bother. When they want to, integrity investigators seem able to establish which computers were used to access confidential police data, and to crack network paths.

Yet it's not a good look, least of all in a force, whose reputation for integrity and judgment has been under some assault, not least from within, over recent years. I have known even representatives from Victoria Police to quote approvingly what some call the "broken window" theory, which holds that the public loses faith in the cops, and in law and order, when they see them ignoring "minor" breaches of the law, or excepting themselves from its operation. Indeed, it is not every police force in Australia which has had one of its own past commissioners, as a more junior officer, fingered for just the sort of anonymous trolling of a person he disliked that Passant complained of.

Thank heavens all of this technology is new.

David Eastman, while a suspect in the investigation of the murder of Colin Winchester complained long and loudly that he was being continually harassed by in-your-face surveillance from AFP detectives. He also complained of harassing telephone calls at home from people who, from what they said, were part of the investigation team. Police admitted surveillance but blandly denied harassment, suggesting that the perception of it was an evidence of Eastman's dangerous paranoia. The Martin inquiry has recently reported that the police surveillance often ventured, deliberately, from the proper to the improper, and had been harrassing.

To the surprise of the investigation team, Telecom did a proper investigation of the harassing phone calls and found that some had originated from AFP headquarters. Tipped off that the matter was going to come to formal notice and inquiry, the murder squad first argued with bland statements, along Victoria Police lines, that the calls could have come from anywhere, or anyone, in the station. But then, or so Justice Brian Martin, reporting recently, seemed to think, a plausible explanation was concocted.

There were times, the 1990 inquiry was told, when police were unsure of whether Eastman was actually in his flat, or whether he had somehow sneaked out. Whenever there were such doubts, a police officer would ring Eastman's number, and, if he responded, hang up. The same technique was also used, from time to time, to check whether the various bugs secreted in the flat were working, since they recorded the ringing and Eastman's expostulations when the caller rang up.

Justice Martin commented that this explanation "initially appeared to be supported by entries in an occurrence sheet which (then Sergeant Tom) McQuillen said was kept as a record of calls made for operational reasons. However on close examination it was clear that the particular handwritten sheet produced was created by McQuillen on the one occasion and was after the three calls were made."

Whatever could this mean? Perhaps we will never know, given the seeming determination of the AFP to ignore, as ancient history, all of the findings of the Martin report. Anyway, if there is to be any sort of inquiry into whether there were any failings by the AFGP, or the DPP, or the ACT Justice system, it seems that the strategy is to string out consideration of a possible retrial of Eastman until everyone forgets.