来历不明[ lái lì bù míng ]

⒈ 指人或物的来路、历史或背景都不清楚。例适新建县有阙氏者，雇一婢，来历不明。——宋·周密《癸辛杂识·郑仙姑》英of questionable antecedents; of dubious background; unidentified; of unknown origin;