Car in bus lane accident who's fault?

my brother was driving but had a lorry in front which was indicating right. my brother went into the left lane which was a bus lane (active) to overtake the lorry but it went left and hit him and knocked him into the curb. the lorry carried on driving and didnt stop. witnesses came to my brother and told him that it wasnt his fault. the driver did come back and took my brother to the office where they worked. there were two and they intimidated him nito writing a confession that it was his fault. my brother did this and gave his insurance details. he did not take the insurance details of the other driver but can be obtained. the police were not called. he has two witnesses that say it wasnt his fault. whos fault do you think it is?