The immediate cause of death is unknown.

造成死亡的直接原因不明。

《牛津词典》

The cause of her death is still unknown.

关于其死亡的原因至今还未知晓。

youdao

Police have not determined a cause of death, and much remains unknown about the circumstances of her demise.

警方暂未确认死因，因此关于她的死因还是个未知数。

youdao

Experts said the cause of death is unknown.

VOA: special.2009.06.16

Her death certificate listed the cause of death as unknown, because Janelle was never able to afford a proper diagnosis, a diagnosis that with care might have saved her life.

CNN: Clinton's September 17, 2007, speech on health care

Although she suffered a head injury and later died, the exact of cause of death remains unknown.

BBC: Leigh-on-Sea case shows 'hidden' elderly domestic abuse

The cause of death remains unknown, but experts agreed it was either from suffocation or poisoning, she said.

CNN: STORY HIGHLIGHTS