Disturbing new details on the murder of Japanese exchange student Natsumi Kogawa are coming to light as her alleged killer's trial gets underway in Vancouver.

Kogawa was found dead on the grounds of the Gabriola House mansion in September 2016, about two weeks after she was reported missing.

On Monday, the first day of trial for accused killer William Victor Schneider, prosecutors told the court that Kogawa's naked body was discovered in a black suitcase that had been left in a hedge on the West End property.

The Crown also revealed in its opening statement that authorities were never able to determine a cause of death. Kogawa's body was decomposing, but not dismembered, and there was no evidence of major injuries.

The jurors heard that toxicology tests showed Kogawa had two prescription sedatives in her system – zopiclone and lorazepam – but that the tests were unable to determine precise levels because of her state of decomposition.

The 30-year-old student's clothes and cellphone were never found.

Schneider is charged with second-degree murder and interfering with human remains, and the 51-year-old pleaded not-guilty to both counts Monday morning.

Kogawa's mother, Emiko Kogawa, attended the first day of trial, and broke out in tears when the accused walked into court. Prosecutors later warned her through an interpreter that she might find the content of their opening remarks disturbing.

Jurors were shown a surveillance image of Schneider and Kogawa together at Harbour Centre Mall on Sept. 8 – one of the last known images taken of the victim while she was alive – and told it played a crucial role in locating her body.

Authorities released the image to the public while they were still hoping to find Kogawa alive. Prosecutors said the accused’s niece recognized his face and told her father, Schneider’s brother, who went to visit him in Vernon.

Schneider was allegedly suicidal and told his brother where police could find Kogawa’s body, according to the Crown. Officers in Vancouver located the missing student's remains with help from a police dog on Sept. 28, and Mounties in Vernon arrested Schneider the same day.

Kogawa was in B.C. to study English at the time of her murder. Prosecutors said she had made friends and enjoyed an active social life, sometimes camping and going to parties.