He was voiced by Bill Flynn.
Edward and Alphonse Elric arrive in Xenotime but are ushered out and accused of identity theft on the basis of the "Elric Brothers" already working in Mugear's employ. The Elrics discover that the imposters are Russell and Fletcher Tringham, the sons of Nash who had once been in Mugear's employ but disappeared. Mugear reveals his work in the production of Red Stones, alchemical augmenters with the ability to mimic the sought-after Philosopher's Stone. Using the material's main ingredient, the Red Water, he seeks to bring Xenotime back to its former glory, as well as make a profit.
Mugear is shown speaking with Lust concerning his plot to create many Red Stones with as-yet unveiled scheme. He also feigns belief in that the Tringham brothers are the Elrics, imprisoning them once the real Elric Brothers make their presence. The full extent of Mugear's plot is revealed. By introducing the Red Water into Xenotime's water supply, pregnant women ingesting the tainted water would have their fetuses remade into catalysts to create the Red Stones. He had approached Nash with this goal and murdered him when the alchemist refused to take part in Mugear's scheme.
The Elric and Tringham brothers confront Mugear who uses the Red Stones to attack them with a gun-like device. Retreating into the Red Water reservoir, the underground route leading there begins to collapse. Refusing to abandon the Red Water, Mugear dies when a large rock falls from the cavern's ceiling onto him.