Senussi and Saif al-Islam, son of the Col. Moammar Gadhafi, are accused of committing crimes against humanity during Libya's civil war in 2011.
The International Criminal Court said Friday the case against Senussi is subject to proceedings conducted by the Libyan justice system and "this decision has no bearing on the case against Saif al-Islam Gadhafi."
The court said it found evidence submitted by Libya was enough to conclude "that concrete and progressive steps are being undertaken by the domestic authorities in the proceedings against Mr. al-Senussi."
Libya says it has the right to try Saif al-Islam if its courts are open and functioning.
Tarek Mitri, U.N. special envoy for Libya, told the Security Council last month the security situation in Libya presents "a formidable challenge" to judicial authorities.