This is the second time Thunberg has been detained at the site, police spokesperson Christof Hüls told CNN Tuesday.
After the group advanced on the coal pit, police were concerned that the “masses of protesters” could set the ground in motion after it had been softened by rainfall during the last few days.
Walshe, 47, pleaded not guilty last week to misleading investigators about his actions around the time his wife went missing.
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