"They might decide to investigate this whole region of space."

The sound repeated, and she decided to investigate, because it hadn't felt quite right.

He used to see light from a distance and decided to investigate the source.

Things go wrong and the 3 decide to investigate the case as a group.

The sun was high when she decided to investigate the hole in the wall.

"No one is supposed to go in there," Tom told himself and decided to investigate.

He decided to investigate that possibility after he'd tried the door at the other end.

The children don't believe him at first, but then decide to investigate.

Having heard the stories, the author decided to investigate them for himself together with a friend.

Why at this particular time, six or seven months after she died, did he suddenly decide to investigate her death?