Lauren Mikaila Biddle, 22, died suddenly during a small gathering at a hillside house in the Christchurch suburb of Clifton on October 22, 2018.
Biddle, a promising American polo player, had been in New Zealand for just over a week.
She had planned to stay in Clifton, working and playing polo, until March last year.
Her family was shocked by the death of their "vibrant, fun-loving" girl.
Joseph Douglas McGirr, a 39-year-old Christchurch civil engineer, was arrested after Biddle's sudden death at his property.
McGirr was charged with supplying Biddle – and another man – the Class-B controlled drug MDMA, also known as ecstasy, and attempting to pervert the course of justice by hiding Biddle's clothing after her death.
He pleaded not guilty and a jury trial began at Christchurch District Court this morning. McGirr did admit a charge of cultivating cannabis today.
The Crown outlined its case to the jury this morning, saying at the heart of the matter lies a small social gathering that went "horribly, tragically wrong".
McGirr, Biddle and two others had been drinking alcohol and smoking cannabis while relaxing in McGirr's spa pool, the court heard.
Midway through the evening, one man left, leaving McGirr, Biddle and another man.
Crown prosecutor Kerry White says McGirr then offered ecstasy to Biddle and the other man.
McGirr, the Crown alleges, prepared and provided three lines of crushed ecstasy on a bread board, which was sniffed by everyone through a little tube.
The trio continued to sit in the spa pool until "very late in the evening".
At one point, when the other man returned to the spa, McGirr told him that Biddle was dead.
The man went over to Biddle, shook her, and when she didn't respond, pulled her out of spa pool and tried to feel for a pulse. McGirr again said she was dead.
The man tried to give CPR and wanted to call an ambulance but the Crown alleges McGirr "became angry and said, 'No'".
In desperation, the other man loaded Biddle into his car and reversed up the steep driveway, where he got out at the top and phoned 111. He continued with CPR.
Emergency services arrived quickly but Biddle was declared dead on the roadside at around 1.20am.
In meantime, the Crown says McGirr was back in the house "tidying evidence of the party", clearing bottles and cans, and throwing Biddle's clothes and belongings over his balcony into an overgrown section below.
He then took them further down the hill, the Crown says, and, using a spade, covered them with leaves and concealed them.
When police first arrived on the scene at around 2am, McGirr was not at home, the court heard. The Crown says it's likely he was burying Biddle's clothing.
At 3.30am, McGirr appeared out of bushes in front of house and made himself known to the police, the court heard.
He was taken to Christchurch central police station where gave a statement and told police what he had done with Biddle's bag and clothing, the Crown says.
At around 12.30pm in the afternoon that day, McGirr returned to the address with police and led them down into the overgrown section and pointed out the partially buried bag, clothing and shoes which he said belonged to Biddle. Police also found seven cannabis plants still attached to garden stakes but which had been uprooted.
The Crown say that the seven cannabis plants are important because they show he knew police were going to come to his house to investigate her death and very likely search his property.
The Crown says Biddle was very drunk - nearly four times the drink-driving limit.
And it was found that she had a high concentration of MDMA in her system which was around 15 times greater than the "normal recreational use" of the drug.
It was such a high level of that it was "well within the range of previously encountered fatal concentration", the court heard.
A post-mortem found her cause of death was most likely a drug overdose that caused a sudden cardiac arrest.
The trial, before Judge Tom Gilbert, is expected to last all week.
