Identity documents (passport, ID card) are taken away.

Your freedom of movement or communication with relatives is restricted.

Wages are not paid or differ significantly from what was agreed upon.

Threats to report you to migration authorities or to have you deported.

Center for Against Human Trafficking and Exploitation (KOPŽI):
Provides support to victims and assistance with law enforcement  
24/7 Hotline: +370 616 91119,  anti-trafficking.lt 

Caritas Lithuania: "Help for Victims of Human Trafficking" program.