/usr/lib/libvtkImagingMathTCL-6.1.so is in tcl-vtk6 6.1.0+dfsg2-6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libvtkImagingMathTCL-6.1.so.6.1
/usr/lib/libvtkImagingMathTCL-6.1.so.6.1