A Malaysian military man who defecated outside the house of a woman he followed home was likely to have lied about his drug use, mental health experts have said.

Muhammad Rizalman bin Ismail, 39, had pleaded guilty to indecent assault on Monday, the morning his trial was due to begin in the High Court at Wellington after following Tania Billingsley to her home on May 10, 2014.

Two other charges of assault with intent to commit sexual violation and burglary were discharged by Justice David Collins.

DAVID WHITE/KEVIN STENT FAIRFAX Former Malaysian diplomatic employee Muhammad Rizalman bin Ismail, 38, arrives at the High Court for his disputed facts hearing in Wellington this morning.

Instead a disputed facts hearing was heard on Friday with Rizalman giving his side of the story publically for the first time.

He told the judge that he had only wanted to be friends with her and talk to her about his problems but accepted he had gone into the house without any trousers or underpants.

The Crown case is that Billingsley had been home alone watching a movie in her bedroom when Rizalman came in without his trousers and underwear.

DAVID WHITE/FAIRFAX NZ Former military attache with the Malaysian High Commission in Wellington, Muhammad Rizalman.

Billingsley looked up and saw him wearing only a shirt and naked from the waist down. She screamed at him to leave. Rizalman put his hands on her shoulders but she managed to push him into the living room then out of the flat before locking him out.

She then locked herself in the bathroom and called police. A flatmate's boyfriend arrived home and challenged Rizalman who was still outside the front door.

Rizalman began walking away but was stopped down the road by the police.

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Rizalman had left New Zealand without facing trial after Malaysia invoked diplomatic immunity, in the belief it did so with the New Zealand Government's blessing.

He returned after extradition hearings were filed in Malaysia.

At the time of the attack he had been working at the Malaysian High Commission as a staff assistant to the Malaysian defence advisor.

Billingsley waived her right to name suppression.

Rizalman admitted to Crown prosecutor Grant Burston he believed in black magic and knew of a spell about having a woman fall in love with you if you defecated outside her house.

He also said he thought an superior officer had put a spell on him.

Rizalman agreed he had not told police, or others, about pooing outside the house because he was too embarrassed.

"So the only time you have had an emergency defecation just happens to be in those 30-40 minutes waiting outside this young woman's house?" Burston asked.

"Yes," Rizalman said.

Burston said: "It was the reason you took off your belt and lowered your trousers and underpants outside this young woman's front door on the patio.

"It was more about black magic than about having to go to the toilet in an emergency."

Rizalman said no, but agreed he had bought synthetic cannabis from a Cuba St shop the week before and followed another woman the day before, as well as going to Mermaids Bar.

He told Burston Billingsley had given him a signal and wanted to befriend him which was way he had followed her home.

He said in Malaysian culture if a woman smiled at you she wanted to get to know you better.

Psychologist Professor Graham Mellsop told the judge Rizalman had scored high on the lying and faking scales in a report, meaning he did not always tell the truth and suggested he was exaggerating his symptoms.

He said the only logical conclusion was his problems had come from drug ingestion.

Mellsop said he accepted there were behavioural changes, like Rizalman forgetting the words of a prayer he said five times a day but he attributed them to more regular substance ingestion.

Rizalman's, lawyer Dr Donald Stevens QC, challenged Mellsop's opinions saying Rizalman had been suffering from anxiety and others had seen the changes in his behaviour.

However Mellsop said he did not think Rizalman was in a state of confusion on the day of the incident since he was subsequently able to give detailed explanations of what he said had happened.

Consultant forensic psychiatrist Dr Justin Barry-Walsh also said he felt Rizalman had not been truthful about his drug intake.

The judge has adjourned the case for a week to hear submissions from the lawyers and make a decision.

HOW THE SAGA UNFOLDED

2014

May 9: Rizalman follows Tania Billingsley from a shop to her home. After a struggle in the house he is arrested by police down the road.

May 10: Rizalman appears in court and his diplomatic status is considered.

Foreign Minister Murray McCully is informed but Ministry of Foreign Affairs and Trade boss John Allen is left out of the loop.

May 12: An informal discussion between officials from Mfat and the Malaysian High Commission leads to Malaysia concluding that New Zealand "offered" an alternative option for Rizalman to be sent back to Malaysia to face charges.

May 21: Malaysian High Commission tells Mfat it will not waive Rizalman's immunity and asks for all charges to be dropped and all documents to be "sealed".

May 22: Rizalman leaves New Zealand and returns to Malaysia. He is hospitalised for psychiatric evaluation.

June 27: McCully hears for the first time that the Malaysians rejected the request for a waiver. Allen hears about the case for the first time.

June 29: The media reports that a diplomat has claimed immunity and left the country. Malaysian media soon report he was one of their diplomats.

June 30: Prime Minister John Key and McCully are adamant that New Zealand clearly opposed Rizalman leaving and wanted him tried, but on legal advice say they can't name him or the country. Malaysian High Commissioner called in for grilling by Allen; she reveals "ambiguity".

July 1: Fairfax Media lawyers succeed in getting court-ordered name suppression lifted so that Rizalman and the country he represents can be named in New Zealand. McCully releases May 10 and May 21 documents showing New Zealand's unambiguous request for a waiver, and Malaysia's refusal. Hours later McCully concedes informal discussions may have created the "ambiguity" about New Zealand's position. He says Malaysia acted in good faith.

July 2: McCully apologises to Key and Allen apologises to McCully but they both refuse to say if resignations were offered. Allen announces an independent review of Mfat's handling of the event. McCully also reveals that a junior staffer in his office was informed about Malaysia invoking diplomatic immunity but never opened the email.

July 9: A district court judge accepts Billingsley's application for her name suppression to be removed and she speaks to the media.

October: A formal request to extradite Rizalman to New Zealand is made. Rizalman waives the need for a formal extradition and agrees to return.

October 25: Rizalman returns to New Zealand and immediately faces a district court.

2015

November 27: A High Court judge is told the trial does not need to go ahead as Rizalman will plead to one of the charges.

November 30: Rizalman pleads guilty to indecent assault and is remanded for further court hearings.