NAIROBI, Kenya  Melitus Mugabe Were, a freshman member of Parliament, could have been one of the keys to unlocking Kenya’s crisis, but he never got the chance.

He was a moderate opposition politician, a self-made businessman who grew up in a slum, and he bridged the ethnic divide. His wife is from another ethnic group, and as Kenya slid into chaos this past month after a disputed election, he shuttled between different communities and tried to organize a peace march.

On Tuesday morning, as he pulled up to the gate of his home, Mr. Were was dragged out of his car and shot to death.

“Whoever did this,” said Elizabeth Mwangi, a friend, “has killed the dreams of many.”

The details are still sketchy, but the shooting appears to have been a planned murder, not a robbery. Word spread fast and led to violence, with opposition supporters rioting across Nairobi, the capital.