CAIRO—The son and one-time heir apparent of late Libyan dictator Moammar Gadhafi announced Sunday his candidacy for the country’s presidential election next month, Libya’s election agency said. Seif al-Islam, who is wanted by the International Criminal Court on charges of crimes against humanity related to the 2011 uprising, submitted his candidacy papers in the southern town of Sabha, 650 kilometers (400 miles) south of the capital of Tripoli, the High National Elections Commission said in a statement. Gadhafi’s son was captured by fighters in the town of Zintan late in 2011, the year when a popular uprising, backed by the NATO, toppled his father after more than 40 years in power. Moammar Gadhafi was killed in October 2011 amid the ensuing fighting that would turn into a civil war. The second-born son to the longtime dictator, Seif al-Islam was seen as the reformist face of the Gadhaf regime before the …