Detectives have arrested a suspect in the fatal shooting of a 67-year-old man on the front porch of a Llano home this week, officials announced Thursday.

A 29-year-old man was charged with murder after he allegedly shot and killed a Caltech scientist in front of a Los Angeles County home.

Carl Grillmair’s work included research using NASA’s Spitzer Space Telescope and focused on galactic structure, dark matter and stellar populations.