A federal judge in Mexico ordered the group accused of killing ICE special agent Jaime Zapata to remain in jail for 40 days.
Prosecutors sought this legal action to gather enough evidence to indict the six men and three women.
The Mexican army arrested all nine individuals, believed to be Zetas members, on Wednesday.
Among them is Julian Zapata Espinoza, who Mexican Army officials say, is the group leader and the man who led the attack on Special Agents Jaime Zapata and Victor Avila on February 15.
All nine men and women are expected to face homicide and attempted homicide charges.
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