Indonesia executed three convicted murderers, including a mother and son, the latest in a spate of state killings bucking a downward trend in the death penalty globally, officials and activists said Saturday. Human rights groups speculated that by ramping up killings, the Indonesian state was trying to demonstrate its authority over its 220 million people after 10 years of often chaotic democratic rule that emerged from decades of dictatorship. "It is likely the government want to improve its image ... as a strong institution," said Zaenal Abidin, from the Legal Aid Foundation, one of several groups calling for last-minute stays of execution. A firing squad executed the mother and son early Saturday in the industrial town of Surabaya on Java island, said their lawyer Soeteja Djajasmita. Sumiarsih, 60, and Sugeng, 44, were convicted of murdering five members of a single family 20 years ago during a dispute over money. The pair go by single names.