She had written me to tell me that our friends Todd and Alice had died in a strange accident that involved a vacuum cleaner.

involved 是动词 involve 的过去分词形式。involve 由前缀 in-（表示"进入"）和词根 volve（来自拉丁语 volvere，意为"滚动"）组成，本义是"卷入、使参与"。在这里表示"牵涉、涉及"的意思，说明吸尘器与这起事故有关联。