Joe Biden as vice president hired one of his son Hunter’s investment-firm staffers as a personal assistant, emails from his son’s discarded laptop show. Anne Marie Person, 34, left Hunter Biden’s Rosemont Seneca Partners in 2014 to join the veep’s staff — and stayed in close contact with her former bosses, keeping them apprised of visiting dignitaries and official events they might have interest in, according to the emails. Rosemont Seneca and its affiliates have come under scrutiny, as the US Department of Justice investigates Hunter Biden’s foreign dealings as part of a possible tax-fraud probe. Hunter Biden secured meetings...