I read in the paper several years back about a girl who was kidnapped and detained by a man for eight years. She literally was kept in a house all that time and was not able to run away. When she did finally manage to get out, she informed the police. But it was too late because the man had committed suicide by then.
When we usually think of being unlawfully detained, we think about police officers and being arrested. But kidnappings by regular people happen all the time.