Greek mythology : The Theban Cycle

Parents: Amphiaraus and Eriphyle
Spouses: Callirhoe, Arsinoe
Descendants: Amphilochus (2), Tisiphone by Manto; Clytius by Arsinoe; Acarnan, Amphoterus by Callirhoe; mythical progenitor of the Alcmaeonids.
Greek spelling: ΑΛΚΜΑΙΩΝ (Αλκμαίων)

Alcmaeon was one of the bigger players in the insane Theban soap opera. Son of the famous Amphiaraus, he was joined by his brother Amphilochus (1) in the expedition of the Epigoni whom he led against Thebes, the oracle at Delphi having predicted success under his leadership. After their success in this venture the brothers, or perhaps Alcmaeon alone, avenged their father's betrayal and death by killing the person responsible for it--their mother. Of course matricide is generally frowned upon and he inevitably ended up being chased by the Erinyes who, as they tend to do in cases like this, drove him mad.

At this point he decided, like all smart people did, to consult the oracle at Delphi about getting his sanity back and the Furies off his back. The oracle suggested that he go to "a land that the sun did not shine upon when he killed his mother." While he was in Delphi he made the best of it and sired two children by Manto, daughter of Teiresias. He left the sanctuary at Delphi for Arcadia, where Oicles received him and sent him on to Psophis, where he was temporarily freed from the Furies' persecution due to the purifying ministrations of Phegeus. While in Psophis he married Arsinoe, daughter of Phegeus. To her he gifted the robe and necklace of Harmonia, which he had taken from his mother and which had been the instruments of Amphiaraus' downfall.

His marital bliss didn't last long before the Furies found out where he was and came after him. When he was asked nicely to leave because things were turning kind of barren in Psophis, he finally decided to heed the oracle's advice and headed to the south-western reaches of mainland Greece at the advice of another oracle. At the mouth of the Achelous river he found "new land" created by the river's silting and was purified by the river god, who also gave him his daughter, the nymph Callirhoe in marriage. Apparently some versions mention the Alphius river which is in Elis but the bit about silting makes the Achelous (of which silting is a characteristic even today) much more plausible, as does the general connection of the family with the areas surrounding it.

Just as he was about to settle down for good, the objects that had brought about his father's death came to haunt Alcmaeon. His new wife did not like the idea of her predecessor possessing the glamorous robe and necklace of Harmonia. He should have known better but set out to recover them anyway. His father-in-law Phegeus smelled a rat when Alcmaeon tried to get the objects back from Arsinoe and, depending on whom you believe, killed him himself or had his sons Agenor and Pronous do it. Either way, the infamous cursed robe and necklace were the undoing of yet another Theban.

E2 Dictionary of Classical Mythology