The Argentine striker has been in talks with Velez Sarsfield about a free transfer.
"We got what we wanted," Gianmichele Gentile told LazioNews24. "A ruling has been past, but we'll have to wait.
"Zarate wanted to terminate his contract, but that has not been granted so he will return to Lazio.
"What the club now have in mind for him I do not know - you'll have to ask him and his agent."