"He was extremely warm, friendly, open," Seidemann said.

After returning to Washington to work for a time, Stevens went back to Libya to help try to rebuild U.S. relations with Moammar Gadhafi's regime. Then, in 2011, as Libyans began to take up arms against the dictator, Clinton tapped him for another role.

"In the early days of the Libyan revolution, I asked Chris to be our envoy to the rebel opposition," Clinton said. "He arrived on a cargo ship in the port of Benghazi and began building our relationships with Libya's revolutionaries."

"He was seen as a popular, personable and hands-on diplomat among State Department staffers who knew him," said Elise Labott, a CNN foreign affairs reporter who knew Stevens.

"He wasn't a pinstripe diplomat. He wanted to get his hands dirty, dig in," she said.

Commanday conveyed a similar impression, saying Stevens was "very happy" to get the post.

"He wasn't looking for a ... cushy ambassador's spot," he said. "He loved the Libyan people and was passionate about helping."

Stevens was well-regarded among Libyans, said Fouad Ajami, an expert on Islamic politics.

"The sadness of it is that Ambassador Stevens worked long and hard for the liberation of the Libyan people from the tyranny of Moammar Gadhafi," he said.

Stevens frequently spoke of an infectious enthusiasm for the country that made him "the only person, in the eyes of the State Department," for the Libya post, Labott said.

The ambassador understood Libya and its dangers, but also saw great promise, said CNN's Zain Verjee, who also knew Stevens well.

"Chris was passionate about Libya," she said. "He cared about the people and saw hope in its future. He told me he knew the dangers but was committed to democracy and diplomacy above all."