  Absorption of fermionic dark matter leads to a range of distinct and novel
signatures at dark matter direct detection and neutrino experiments. We study
the possible signals from fermionic absorption by nuclear targets, which we
divide into two classes of four Fermi operators: neutral and charged current.
In the neutral current signal, dark matter is absorbed by a target nucleus and
a neutrino is emitted. This results in a characteristically different nuclear
recoil energy spectrum from that of elastic scattering. The charged current
channel leads to induced $\beta$ decays in isotopes which are stable in vacuum
as well as shifts of the kinematic endpoint of $ \beta$ spectra in unstable
isotopes. To confirm the possibility of observing these signals in light of
other constraints, we introduce UV completions of example higher dimensional
operators that lead to fermionic absorption signals and study their
phenomenology. Most prominently, dark matter which exhibits fermionic
absorption signals is necessarily unstable leading to stringent bounds from
indirect detection searches. Nevertheless, we find a large viable parameter
space in which dark matter is sufficiently long lived and detectable in current
and future experiments.
