Mathnet First Season, Second Mystery Series.
From Square One TV episodes (1986)
Thanks to Tony DuMont for the original show clips:
http://www.youtube.com/watch?v=E07owREetJU Part 1
http://www.youtube.com/watch?v=XST1vZi4YCo Part 2
http://www.youtube.com/watch?v=EORcTnZ3Ab0 PArt 3
http://www.youtube.com/watch?v=wcrjJKKlVqA PArt 4
http://www.youtube.com/watch?v=qiIBpceAWgQ Part 5