Mtetwa was released by a court after eight days in jail for allegedly obstructing justice. The alleged intimidation of activists and pro-democracy groups come ahead of elections expected in July.
A visibly tired Mtetwa walked from the High Court in Harare in the company of two colleagues and her lawyer after her release papers took several hours to complete. She told reporters she believed she had been targeted by police.
"It is a personal attack on all human rights lawyers but I was just made the first example. There will be many more arrests to follow as we near elections," Mtetwa said.
"The police were all out to get me. They wanted me to feel their might and power because I call myself a human rights lawyer and I felt it."
Mtetwa was arrested on March 17 along with four officials from Prime Minister Morgan Tsvangirai's party.
The officials are accused of illegally compiling information on high level corruption and are schedule to appeal for bail on Tuesday. Mtetwa was accused of shouting at police officers who were conducting a search at Tsvangirai's staff offices when she demanded to see a search warrant.
'Illegal, unlawful and undemocratic'
Mtetwa and the four officials denied any wrongdoing. She said she merely told the police that "what they were doing is illegal, unlawful and undemocratic".
High Court Judge Joseph Musakwa ruled early on Monday that Mtetwa was following professional legal procedures when she demanded to see a search warrant from police at the offices of the four officials.
"She was entitled to be appraised of the legality of the search," Musakwa said.
After her release, Mtetwa said she was not well-treated while in police custody. She was not allowed to take a bath and was denied access to her lawyers and family. But she said she would not give up the fight for human rights.
"I will not be cowed," Mtetwa said. "There has to be mutual respect between police and lawyers because we will all be doing our job."
'Deeply concerned'
Critics cited Mtetwa's prolonged jailing as the start of a fresh wave of political intimidation against President Robert Mugabe's opponents by loyalist police and judicial officials ahead of elections.
The European Union (EU) said in a statement on Monday that Europe's governments were "deeply concerned" by Mtetwa's arrest and the onslaught against civic groups as Zimbabwe prepares for elections to end the shaky and dispute-ridden coalition government.
The European bloc conceded that a referendum vote on March 16 on a new constitution was "credible" and reflected the free will of about three-million voters who cast their ballots and overwhelmingly accepted the reformed constitution, EU spokesperson Carl Skau said on Monday.
As a result the EU suspended with immediate effect travel and banking bans on 81 leaders of Mugabe's party.
But Mugabe, his wife, military, police and security chiefs and several others key loyalists remained on the ban list.
The restrictions were imposed in 2002 to protest the human rights record, violence, corruption and allegations of vote-rigging by Mugabe's party in past elections.
Regional mediators forged the coalition government between Mugabe and Tsvangirai after the disputed and violent elections in 2008.
Intimidation
So far this year, four rights and advocacy groups have been raided by police searching for alleged subversive materials relating to their activities campaigning for free elections and an end to political intimidation and human rights abuses that have dominated past elections.
Mtetwa was scheduled to act as lead defence attorney in the trial, resuming on Monday, of 29 supporters of Tsvangirai's party charged in the murder of a police inspector in an impoverished township suburb in western Harare.
Most of those suspects were denied bail for more than a year. Defending them, Mtetwa noted that six police officers charged in the assault and murder of a theft suspect received bail within a month of their detention.
The officers are still to go to trial in that case, which was opened nine months ago.
Swaziland-born Mtetwa moved to Zimbabwe in 1983. She represented key leaders in Tsvangirai's party, including its treasurer Roy Bennett, now in self-imposed exile after repeated threats.
She has also defended journalists and prominent rights workers, some of whom were tortured, according to evidence in court, and held incommunicado without charge for several weeks late in 2008.
Obstructing justice
Last week police ignored a High Court order to free Mtetwa and on Wednesday the lower Harare Magistrate's Court ordered her held in custody to reappear in that court on April 3.
Charges of obstructing justice carry a maximum of two years imprisonment.
The judge said Mtetwa should not have been denied bail because of her "professional standing". He said the police officers conducting the search could have "easily subdued her because she is a woman" if they felt she was hindering them from doing their job.
"She is a lawyer of many years, with a forceful, combative and at times aggressive personality but she remains professional and dignified" when doing her job, the judge said.
Mtetwa is a recipient of an array of awards from international jurists' groups, including the American Bar Association over a distinguished career of three decades.
Mtetwa is known for her feisty and outspoken style and for quickly responding to calls for representation around the clock by activists and journalists held by police.
Media freedom groups said her detention, the first time she was jailed, left independent reporters and rights campaigners fearful of being left without her voice.
The state's Sunday Mail criticised Mtetwa for thinking she was "untouchable" and said her "stage-managed antics in and outside the courts" earned her "dubious awards" from lawyers groups worldwide.