While little or none of their own writings have been preserved, the Sadducees seem to have indeed been a priestly group, associated with the leadership of the Temple in Jerusalem. Possibly, Sadducees represent the aristocratic clan of the Hasmonean kohen, who replaced the previous high priestly lineage that had allowed the Syrian Emperor Antiochus IV Epiphanes to desecrate the Temple of Jerusalem with idolatrous sacrifices and to martyr monotheistic Jews. The Jewish holiday of Hanukkah celebrates the ousting of the Syrian forces, the rededication of the Temple, and the installment of the new Hasmonean priestly line. The Hasmoneans ruled as "priest-kings", claiming both titles high priest and king simultaneously, and like other aristocracies across the Hellenistic world became increasingly influenced by Hellenistic syncretism and Greek philosophies: presumably Stoicism, and apparently Epicureanism if the Talmudic tradition criticizing the anti-Torah philosophy of the "Apikorsus" אפיקורסוס (i.e., Epicurus) refers to the Hasmonean clan qua Sadducees. Like Epicureans, Sadducees rejected the existence of an afterlife, thus denied the Pharisaic doctrine of the Resurrection of the Dead.
The Dead Sea Scrolls community, who are probably [[Essenes]], were led by a high priestly leadership, who are thought to be the descendents of the "legitimate" high priestly lineage, which the Hasmoneans ousted. The Dead Sea Scrolls bitterly opposed the current high priests of the Temple. Since Hasmoneans constituted a different priestly line, it was in their political interest to emphasize their family's priestly pedigree that descended from their ancestor, the high priest Zadok, who had the authority to anoint the kingship of Solomon, son of David.
Most of what is known about the Sadducees comes from Josephus, who wrote that they were a quarrelsome group whose followers were wealthy and powerful, and that he considered them boorish in social interactions (see Josephus's [http://www.gutenberg.org/catalog/world/readfile?fk_files=2529&pageno=105 Wars of the Jews, Book II, Chapter VIII, Paragraph 14]). We know something of them from discussions in the Talmud (mainly the Jerusalem), the core work of Rabbinic literature Judaism, which is based on the teachings of Pharisee Judaism.