His best friend died under questionable circumstances.

他最好的朋友在不明的情况下死了。

《柯林斯英汉双解大词典》

I recalled the fate of Marco Polo who died under a cloud of contempt.

我想到了马可波罗的命运，他是在一团憎恶之云的笼罩中弃世的。

youdao

By 1997, however, its claims couldn't be substantiated, and one of the company's geologists died under mysterious (and ambiguous) circumstances.

但结果连一勺的金子都没找到。到1997年，Bre - X没能兑现承诺，公司的一位地质学家神秘死亡(有争议)。

youdao

An inquest takes place when someone has died under suspicious or unknown conditions.

VOA: special.2009.08.31

Politicians from both sides have said that, because more people died under communism than under fascism, the law is justified.

VOA: standard.2009.12.16

Bangladeshi media say, since the February massacre, nine border guards have died under suspicious circumstances.

VOA: standard.2009.03.26

His mother, older sister, and two-year-old nephew all died under the rubble that day.

NPR: Lebanese Families Cope with War Deaths

The worst seemed to be over, when, in midafternoon, his computer died under his eyes.

NEWYORKER: Outage

The official version of events said he died under the plastic surgeon's scalpel while trying to change his identity.

BBC: Heriberto Lazcano: The fall of a Mexican drug lord