In Harry Potter and Half-Blood Prince, Dumbledore tells Harry that the Ministry of Magic arrested Morfin Gaunt because they thought he killed the Riddle family. I know every magical child under the age of 17 had the Trace placed on him/her, and Voldemort was younger than 17 when he murdered his father. Shouldn't the Ministry have known that Morfin wasn't the one who killed the Riddles, because he was a lot older than 17? Why did the Ministry send him to Azkaban?

Edit: I know the spell doesn't say who has done the magic but it can say there was a magical child there.

  • I'm not sure where, but I think in one of the books, they can't tell who does magic, just the general area. In magical households, they leave it to the parents to enforce the underage usage. They were able to catch Harry because he was the only wizard in his house.
    – xecaps12
    Apr 7, 2012 at 1:54
  • It was the second book I was thinking of. Dobby does magic to get Harry in trouble, and the Ministry sends Harry a cease and desist letter.
    – xecaps12
    Apr 7, 2012 at 2:29
  • @xecaps12 that was in same book that dumbledore mentioned that (half-blood prince). I know that, but as I said obviously that wasn't morfin anyway!
    – undone
    Apr 7, 2012 at 2:49
  • Tom was supposed to be at school at the time, thus he would be allowed to do magic, and it wouldn't have set of any alarms. I'm not sure if the trace had the ability to track where they were or not.
    – xecaps12
    Apr 7, 2012 at 3:03
  • I haven't found a satisfactory answer to this question either. The question you ask is similar my question here scifi.stackexchange.com/questions/10785/…
    – Dason
    Apr 7, 2012 at 4:34

2 Answers 2


Dumbledore describes why they believed it was Morfin:

'The Ministry... knew that a convicted Muggle-hater lived across the valley from the Riddle house, a Muggle-hater who had already been imprisoned once for attacking one of the murdered people.

'So the Ministry called upon Morfin. They did not need to question him, to use Veritaserum or Legilimency. He admitted to the murder on the spot, giving details only the murderer could know. He was proud, he said, to have killed the Muggles, had been awaiting his chance all these years. He handed over his wand, which was proved at once to have been used to kill the Riddles.'

So they had means, motive, and opportunity, along with a confession. All without any real investigation. Even Morfin believed he had been the one to kill them:

[Harry:] 'And Morfin never realised he hadn't done it?'

'Never,' said Dumbledore. 'He gave, as I say, a full and boastful confession.'

When Harry asked about Tom being under-age, Dumbledore just says they can't tell who cast it:

'But how come the Ministry didn't realise that Voldemort had done all that to Morfin?' Harry asked angrily. 'He was under age at the time, wasn't he? I thought they could detect under-age magic!'

'You are quite right - they can detect magic, but not the perpetrator: you will remember that you were blamed by the Ministry for the Hover Charm that was, in fact, cast by -'

'Dobby,' growled Harry; this injustice still rankled.

That doesn't explain why they glossed over Tom's trace, he was 16 so it should have registered. Perhaps because he was a Prefect moving up to Head Boy. Maybe they did question him, and he said he came to find his Uncle and just happened to be nearby when Morfin killed them - that seems to me the likeliest.

All quotes from HBP, ch. 17 (pp.343-344, British first ed. hardcover)

  • 7
    Regarding the trace, I also wouldn't count out the possibility that Voldemort had found a way to completely surpress it. Dec 11, 2015 at 20:11
  • @leftaroundabout: He didn't even have to. Since he made Morfin admit to the murder, he could easily have said he tried to use a bit of magic to stop him but failed.
    – user21820
    Apr 15, 2019 at 6:23

I read somewhere in the books (I think book 7?) that if the house one lives in is a magical one they can't tell who cast a spell, or whether the person is underage or not. This is different to a Muggle household where the only (other) people are Muggle adults, and only one or two children who might be witches/wizards.

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