Assaulted at work. HR didn’t follow company policy.

Location: Ontario, Canada.

In short summary, I was physically assaulted by a team leader at work. I reported it to HR, and gave the HR specialist my statement via email. She had nothing to do with the investigation, but she handed my statement off to the HR manager apparently. I did not hear anything back for a while, until I received a resolution letter, stating no basis for my allegations. In our company policy, it clearly states that the victim (me), the alleged perpetrator, and any witnesses will be interviewed as part of a thorough investigation. But the HR manager doing the “investigation” never once talked to me. He even had someone else deliver the resolution letter to me. No one talked to me during the investigation. I contacted the ministry of labour, and they said their only purview is to make sure a resolution letter was hand delivered to me (and the HR manager knows this). It is not their purview to make sure an investigation was done properly, or even done at all. I did contact a lawyer, but they are very expensive. Are companies allowed to not follow their own policies in regards to physical assaults? Everything is kept confidential, but I know for sure I was not interviewed or even spoken to during the investigation, despite company policy. Any insight would be helpful. Also, I must add, that the days following my assault (before and during the investigation), the team leader who grabbed me was still working in close proximity to me, and sometimes literally right beside me. Thanks for reading.