Retired FBI agent urges rapid DNA testing in Guthrie case: 'You don’t wait for FedEx on Monday morning'

An apparent large-scale operation Friday night tied to the disappearance of 84-year-old Nancy Guthrie marks a "significant escalation" in the Arizona case, with investigators now racing to canvas neighborhoods and fast-track critical DNA evidence, according to a retired FBI agent.

Acting on a lead, the Pima County SWAT team and the FBI on Friday executed a federal search warrant at a Tucson-area home roughly two miles from Guthrie's home, detaining three people.

A fourth person was...