The Clone Wars

"Wears the symbol of Chancellor Valorum and is believed to be his personal attache. His association with the cabinet of the high Chancellor is known."
―A file on Silman accessed by the Jedi[src]

Silman was the aide of Chancellor Valorum that accompanied Jedi Master Sifo-Dyas on a diplomatic mission to Oba Diah about ten years prior to the start of the Clone Wars. They were supposed to deal with a sudden increase in illicit smuggle of spice by the Pyke Syndicate. Soon after their arrival there, though, the negotiations were postponed since the Jedi High Council insited on Sifa-Dyas´s participation in another diplomatic mission on Felucia, where a skirmish divided the native tribes. It is to be assumed that Silman joined Sifo-Dyas on his mission since both were supposedly killed on Felucia. It is later discovered that their shuttle was shut down by the Pyke Syndicate on behalf of Dooku.

Sifo-Dyas had joined forces with Dooku after the Jedi High Council did not listen to his concerns on a vision of a coming war for which the Jedi would need an army. After Sifo-Dyas served his purpose to him Dooku had the Pyke Syndicate assassinate them. Unbeknown to Dooku Silman survived the crash on Oba Diah moon and was taken prisoner by the Pyke Syndicate as insurance against the Sith.

In 19 BBY their shuttle was detected and recovered by Plo Koon, which led to an inspection of Sifo-Dyas´s disapperance and death. This ultimatly brought Obi-Wan Kenobi and Anakin Skywalker to Silman, who was still imprisoned by the Pyke Syndicate. They questioned him on his time spent with Sifo-Dyas. Silman, who had lost most of his mental lucidity during the time of his imprisonment, told them the Pykes were not the one who iniciated their assassination. Before he could tell them further details he was killed by Dooku who choked him with The Force.

Dooku was sent by Darth Sidious who was alarmed by the Jedis´ interest in these activities. He had knowledge of this inspection because Yoda questioned him since the file with further informations on Sifo-Dyas´s mission on Felucia and on his death in the Jedi archives was sealed by the Supreme Chancellor´s office.