But Colombians could still reject the deal, which ends a 50-year conflict, in a national referendum on Sunday.
The country's FARC rebels have promised to quit the drug trade, but other groups are ready and waiting to take control.
The biggest hurdle is obtaining public support for the peace agreement in a referendum to be held on October 2, with polls hinting that a Brexit-style upset is possible.
The Revolutionary Armed Forces of Colombia, or FARC, is one of the few remaining remnants of the wave of Marxist-inspired Latin American guerrilla armies that swelled during the Cold War.
President Juan Manuel Santos said he expects to wrap up talks with the Revolutionary Armed Forces of Colombia, or FARC, by July 20, though he appears less confident of the peace deal's ratification in a subsequent re
Latest agreement between government and FARC rebels comes within negotiations to end 51 years of civil conflict in Colombia nearing "home stretch," experts say.
The possible probe comes as the government moves closer to signing a peace deal with rebels.
FARC leader says the group is completely committed to seeing the peace signed, and imagines returning to his home town once it is.
Their handshake in Havana, although awkward, provided a stirring image of reconciliation after decades of mutual contempt and distrust between Colombia's government and largest rebel army.