  We study one dimensional {\it extended} Kondo lattice model, described by the
$t-J$ Hamiltonian for conduction electrons away from half filling and the
Heisenberg Hamiltonian for localized spins at half filling. Following
Shankar,\cite{Shankar} we find an effective field theory for this model, where
doped holes are represented by massless Dirac fermions (holons) and spin
excitations are fractionalized into relativistic bosons (spinons). These holons
and spinons interact via U(1) gauge fluctuations. Effects of Berry phase to the
localized spins disappear due to the presence of Kondo couplings, causing the
spinon excitations gapped. Furthermore, the gauge fluctuations are suppressed
by hole doping. As a result, massive spinons are deconfined to arise in the
localized spins unless the Kondo hybridization is strong enough. When the Kondo
hybridization strength exceeds a certain value, we find that the localized spin
chain becomes critical. This indicates that the present one dimensional Kondo
lattice model exhibits a phase transition from a spin-gapped phase to a
critical state in the localized spin chain, driven by the Kondo interaction.
