12 year old arsonist

I am 90% certain that my son (12) was involved with a fire at an abandoned house close to his school and our home.He was due back at 4pm, but turned up at 4.40pm covered in mud When asked why he was late he said he had been up the abandoned house on the hill with 2 other boys, which was a lie as there isn't any over the fields or hill.A facebook group for our area then put up a post regarding a 2 fire engines at the abandoned house on a certain street...... Which we know is abandoned. I asked what time this was roughly, and they said 5pm.My son then changed his tune and aid he went to that abandoned house first, then over the fields and up the hill. He said that they went round the back of this house, but got scared so ran off and went to the fields.I have spoken to the school this morning, who will speak to all 3 boys.... One of them is going to crack eventually.Once I know the full story, I am going straight to the police to report them.I am deeply ashamed of him...... And worried about him, and his future. He's still young, but I feel that I need to nip this is the bud right now...... I don't want him to have a record, but he needs to know his actions have concequences. He's never done anything like this before.Am I doing the right thing?Ps ... I'm in the UK, so UK law would apply. via /r/Parenting https://ift.tt/2PgM6cA