They say a 19-year-old suspect turned himself into police on Monday.
Maqsood Ahmed was injured last October when he was attacked while carrying a night deposit after closing his money-lending business.
Ahmed, who was 55, was transported to hospital where he died of his injuries.
A woman who was employed by Ahmed was not harmed.
Another 19-year-old man was arrested last month.
Jean Bertrand Havyarimana and Lloyd Kollie are both charged with robbery and second-degree murder.
Police say a third man who is in custody on unrelated charges is to be charged with robbery and accessory after the fact.