The convicted stalker adopted "increasingly covert" tactics to unsettle the lawyer and one of her friends, in whom he said he had taken "a romantic interest".

This case marks the third occasion Steven Black, aged 30 at the time of his latest offending, has been prosecuted over crimes involving the same victims.

The man also known as Sky Black pleaded guilty in the ACT Magistrates Court on Tuesday to three counts of using a carriage service to harass.

Federal prosecutor Hannah von Forell withdrew a further 25 charges.

Agreed facts tendered to the court show that when Black was sentenced in January 2020 over his second set of crimes involving the same victims, he was placed on a series of good behaviour orders spanning two years.

But just three months later he began incessantly ringing his former lawyer, who once represented him in a legal matter in 2015.

On 32 days between April and July last year, Black blocked his phone number and rang the woman 117 times, hanging up almost immediately each time.

During June and July 2020, he also harassed the woman on social media by publishing numerous "symbolical, suggestive and cryptic" Facebook posts about her.

He also requested to follow her private Twitter account three times, always using different accounts that were not in his name.

Black's former lawyer told police she had started avoiding public places because she was worried about running into him, having felt "physically sick and frightened" whenever he contacted her.

"She describes the ongoing, prolonged attempts at contact as obsessive and unwanted and is at a loss on how to make him leave her alone," the agreed facts say.

"She is scared, anxious and concerned by his ongoing behaviour towards her and people she knows."

The facts show that Black also harassed one of the woman's friends, in whom he took "a romantic interest" after viewing her Facebook profile.

Over more than three weeks in July last year, he posted several things about her on Facebook and tried to follow her on Instagram using an account that was not in his name.

This woman told investigators she was "alarmed and concerned" about Black's persistent behaviour, having been a victim of his in the past.

She said she felt panicked and had a "fight or flight" response when Black tried to follow her on Instagram.

"She is worried that [Black] may be watching, monitoring or following her," the agreed facts say.

"The contact is unwelcome. She is uneasy that a man she has never met and has never had anything to do with is contacting her."

The facts say that since Black first met his former lawyer in 2015, his behaviour towards her and people she knows "has become increasingly covert and harder to detect".

His offending initially evolved from unsophisticated physical stalking like turning up at her workplace to online harassment, which at first involved contacting the victims using social media accounts in his own name and posting things that named them.

The most recent crimes were again more difficult to trace, given they involved the use of a private phone number, social media accounts in other names and posts that did not explicitly identify the women.

According to the agreed facts, Black has erotomania, which is described as "a delusional disorder in which he believes individuals are in love with him".

Magistrate Louise Taylor on Tuesday committed Black, who is on bail, to the ACT Supreme Court for sentence.

Black will appear in the superior court for directions next Thursday.