In Rolfsen's Knots and Links there is an exercise to show the equivlance between the the JCT and another theorem:
JCT: If $J$ is a simple closed curve in $R^2$, then $R^2-J$ has two components, and $J$ is the boundary of each.
TH: If $L$ is a closed subset of $R^2$ which is homeomorphic with $R^1$, then $R^2-L$ has two components, and $L$ is the boundary of each.
I understand that $L$ can't be bounded, else it will be compact and not homeomorphic to $R^1$. Also $L$ is not homeomorphic to $J$ since removing a point from $R^1$ leaves it disconnected but not $J$. Kindly provide hints on how to proceed.