Kelley arrived at Mortlake in 1582 under the name Edward Talbot, and within days had replaced Dee's previous scryer. For seven years he was the sole channel: Dee saw nothing in the crystal and recorded what Kelley reported seeing and hearing. Every word of the Angelical corpus reaches us through one man's account of what he saw in a stone, written down by another man who trusted him. That is the evidential situation, and no treatment of the system is honest without stating it.
Whether Kelley was a fraud is genuinely unsettled and probably unsettleable. The material is intricate far beyond what a casual deception would require, the letter tables, the language with its own consistent orthography, the calls, and he repeatedly tried to quit, complained the spirits were evil, and once burned some of the books. That is not the behaviour of a man running a simple confidence trick, though it is compatible with several less simple ones. The episode that has always weighed against him is the session at Trebon in 1587 at which he reported the angels commanding that the two men share their wives; Dee complied with great distress, and Kelley got out of the partnership shortly afterwards.
He then had the more lucrative career. Emperor Rudolf II took him up as an alchemist, knighted him, and eventually imprisoned him when the promised transmutations did not arrive.
The death is a mess and is usually reported with false confidence. Dates given range from 1595 to 1597 or 1598, at Hnevin castle at Most in Bohemia. The familiar story, that he fell attempting to escape and died of the injuries, traces to a letter Thomas Browne wrote to Elias Ashmole in 1674, second-hand from Dee's son, some seventy-odd years after the fact, and in Browne's own account Kelley survives the fall with a broken leg and is imprisoned again. A separate contemporary report has him poisoning himself. There is no grave, no death record and no reliable date; a precise day should be treated as invented.