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.