From BibleWiki
Antiochus III. the Great was succeeded by his elder son,
Seleucus IV. Philopator (187-75). Seleucus secured the return of his younger brother
Antiochus IV. Epiphanes, who lived as a hostage in
Rome, by sending his own son
Demetrius thither instead. Before Antiochus arrived home, Seleucus had been murdered by his minister
Heliodorus; the former was thus able to take possession of the Throne, which really belonged to his nephew
Demetrius.