Solution (source code)

= Solution

The likelihood is
$$
e^{-\sum_iX_i+n\theta}\mathbf1_{\{\theta\le X_{(1)}\}},
$$
so $\widehat\theta_n=X_{(1)}$. Regular asymptotics fail because the support $[\theta,\infty)$ depends on $\theta$ and the likelihood maximum lies on its boundary.