The most likely event is #2. I would guess a likely reconstruction of the sequence in these steps: a) The photo was from a police fil; b) the police file was accessed by one of the parties lawyer/s; c) the lawyer/s or people close to the party gave the picture to a journalist or anyway to third person; d) the journalist or the person sold the photos to either i) sold the formally but illicitly to Barcroft or another media company; ii) gave/sold them informally to his/her newspaper or a media subject; iii) gave/sold them informally to another person; in the case d.(i), the last step is that someone or some subject sells picture to Barcroft claiming an unjustified copyright. In the other cases there may be no subject who claimed an unjustified copyright except Barcroft, but anyway the copirygthe was illicitely created/transferred. In any event, there is certainly a copyright use violation (unjustified use of copyright) along the proces of handling the photos, at some point of the chain.
This does not imply that some officer, nor that some lawyer nor that a party committed anything of criminal nature.
The copyright violation itself might have or not have a criminal content but, strictu sensu, an issue of illicit use of coryright could be only brought to court by a subject who owned the copyright and was damaged by it, or anyway who was damaged by its illicit claim.