“取证”常见的英文表达是 “collect evidence” 或 “obtain evidence”。
collect evidence：侧重于通过调查、搜查等方式主动去收集证据。例如：The police are collecting evidence at the crime scene.（警方正在犯罪现场收集证据。）
obtain evidence：更强调通过合法途径或努力获取到证据，语义上稍正式一些。例如：The lawyer worked hard to obtain evidence that would support his client's case.（律师努力获取能支持其当事人案件的证据。 ）