  Within type-I seesaw mechanism it is possible to have large (order one)
light-heavy neutrino mixing even in case of low right-handed neutrino mass
scale (of the order of GeV). This implies large lepton flavor violation. As
example we consider the process $\mu \to e \gamma$ that can have a branching up
to $10^{-8}$ within type-I seesaw (in contrast with the tiny value $10^{-54}$
expected). Such an enhancing of lepton flavor violation can be used to
constraint the parameter space of long lived particle experiments.
