[Verginius Rufus]

I looked at the link you provided. Although it cites Diogenes Laertius, it goes beyond what he says about Epimenides--there is nothing in Diogenes about the Unknown God.

Diogenes (1.110) mentions the plague and how the Athenians were told by the Pythian priestess to purify their city, so they sent Nicias son of Niceratus to Crete to ask the help of Epimenides. He came in the 46th Olympiad (595-592 B.C.) and stopped the plague in this way:

He took sheep, some black and some white and led them to the Areopagus. There he let them go wherever they wished, instructing those who followed them to mark the spot where each sheep lay down and offer a sacrifice to the local god, and thus the plague was stopped. For this reason even to this day it is possible to find in the villages of the Athenians anonymous altars, which are memorials of this expiation.

According to Diogenes Laertius, before this Epimenides had gone to sleep in a cave and woke up 57 years later, and that is why he had become famous.

[Verginius Rufus]

Aristotle in his Athenian Constitution briefly mentions Epimenides of Crete and his cleansing of the city, but has nothing about sheep or altars.

[Trumpinator]

I took it from this source:

Paul announced what had waited six centuries for utterance. Yahweh, the Judeo-Christian God, was anticipated by Epimenides’ altar to the unknown god. He was not a “foreign god” as his adversaries claimed (v.18) but a God who had already intervened to bring help in the affairs of Athens.

http://christiansincrete.org/news/to-an-unknown-god/