Shifter

Shifter (300)

I'd been chasing you for six years. I almost had you in Montreal. I chased you out of Jamaica. Missed you again in Macau. You'd think I'd know you anywhere. But, as I stood in the terminal scanning the new arrivals, I knew you could be anyone.
That's the problem with your reptilian species, you just won't pick a face.

When you aliens arrived, we didn't really think you were a threat. When it was discovered that you could shift we thought, "How cool." But, then we found out that you were definitely a threat and you were far from cool. You are a particularly nasty specimen. Your thirst for human blood made you easy to follow...too easy.

But, now, I had the upper hand. I was ahead of you. Now, I could stop you. But, I had to spot a shape shifting alien on the crowded concourse of the Denver International Airport.
People filed past me. Every shape, size, and color our planet has to offer. I studied each of them; the lawyer in neat business suit, the tourist in flowered shirt and sunglasses, the surfer in Baja pullover and sandals. Boom, got you. I pulled my 357 revolver and walked through the crowd firing point blank at your Baja pullover. I put six shots center mass. Dropped you cold.

After the screaming stopped, the panic eased, and the terminal was roped off, I stood looking down at your grey-green reptilian face. In death you wear your own face. "How did you know it was him," lead TSA liaison Malone asked.
"Open toed sandals," I replied, nudging your foot with my own. "Three toes! His feet didn't shift."
Malone snatched the radio off his belt,"This is Malone. New orders: All passengers remove shoes prior to boarding."