Moses was with Elijah on the Mount of
Transfiguration.
"And it came to pass about an eight days
after these
sayings,
he
took Peter
and John
and James,
and went
up into a
mountain
to pray.
And as he prayed, the fashion of his
countenance was altered, and his
raiment was white and glistering.
And, behold, there talked with him two
men, which were Moses and Elias:"
Luke 9:28-30
It's possible Moses is the other Witness.