Mukoko testified earlier this year that she had been tortured and assaulted in jail. The defendants appeared with bloodied, swollen faces during court appearances late last year.
Wayne Bvudzijena, a police spokesman, said: "It is their prerogative to pursue any legal recourse with regard to any perceived violence they allege may have happened.
"The police will also advance argument why they can't be held liable for anything done to Jestina and the others."
"It is their prerogative to pursue any legal recourse with regard to any perceived violence they allege may have happened"
Mukoko and the others were accused of plotting to overthrow Robert Mugabe, the Zimbabwean president, charges that were widely denounced as trumped up and politically motivated.
Mukoko was taken from her home in early December and held at an undisclosed location until being jailed on December 23.
She was freed on bail in March, only to have a Harare magistrate revoke that in May, prompting international criticism.
Some analysts saw the decision to drop charges as a new willingness by judges loyal to Mugabe to meet demands for reforms.
Mugabe formed a unity government with Morgan Tsvangirai, the former opposition leader and now the country's prime minister, in February.
Tsvangirai said the case undermined the coalition and called for the dropping of charges against all activists.
Hundreds of pro-democracy activists went missing in the wake of Zimbabwe's disputed elections in March 2008.