Source? By which I mean, can you produce anything from the BBC, CNN, or any official US gov't and/or police source suggesting that this is true?
Otherwise, it's just ugly rumour and innuendo perpetrated by people with an agenda to promote. And you're letting them use you as their mouthpiece. Heck, I'd give even odds there are trolls/foreign agents busy at their computers right now, trying to use this tragedy to sow political and social ******* in the US. They dress themselves up as free-thinking patriots who just want the "truth". And the more people like you buy into it, the more successful they are.
From the BBC: "US officials say there is no evidence to suggest Kelley was linked to organised terrorists. He was not a member of First Baptist Church where the shootings took place but had ties to the church through family members,
San-Antonio Press-News reports."