The correct option is D partner
'Accomplice' means person who helps the one who commits the crime. So, the meaning of this word will be Option D 'Partner'. Partner is a person whom we are closely involved in some way. Option A 'Friend' means companion. Option B 'colleague' is the fellow worker in office or business. Option C 'companion' means a co-worker or whom we accompany. The context of the sentence is that police caught the thief but his partner escaped. So, the best fit is Option D, partner. other options A, B and C being incorrect.