A maniac who slashed three elderly straphangers at Grand Central Terminal before he was shot dead by cops only kept his machete as protection, his friend claimed. Family friend Deborah Brown refused to believe deranged attacker Anthony Griffin could have committed the crime — even though she admitted he suffered from mental health issues and carried a machete around with him, she said. “If he did do that – they’re saying he did this – I wanna see proof of it,” Brown, the mother of Anthony