The phrase "main suspect" refers to the person who is thought to be the most likely to have committed a crime or wrongdoing. They are the primary person that investigators focus on during the investigation process. Full definition
Gidi (Tzahi Grad), the father of the latest victim and renegade police detective Micki (Lior Ashkenazi), kidnap main suspect Dror (Rotem Keinan) after he is released from jail due to the police mishandling his arrest. (shepherdexpress.com)
The Okahs were main suspects in the October 1, 2010 independence day bomb blasts in which many Nigerians were killed. (nigeriapoliticsonline.com)
Their main suspect was Mr. Greenberg, according to emails between Ms. Williams, her lawyer and a Portland police officer that were reviewed by The Times. (cnbc.com)