Former Colombian President Alvaro Uribe is accusing his successor of orchestrating the arrest of Uribe's brother to squash dissent. The two politicians were once close but are now bitter rivals.
Friday's tweet is the former leader's first public response after the arrest of Santiago Uribe on Monday. The brother is accused of involvement in murders and forced disappearances while helping form a far-right death squad in the 1990s.
The death squad allegedly plotted dozens of slayings from an Uribe family cattle ranch in northern Antioquia state. Santiago Uribe has long denied any involvement in the killings.
President Juan Manuel Santos said on Thursday that the times when government institutions were used for political persecutions had passed and would not come back.