I don't remember much from the book:
A ship is doing exploration when it finds a planet where it looks like the whole planet is cultivated, but no life forms are detected. There are only harvesters and seeding machines on the planet. They wait to see what will happen to the harvest. But then, an alien spaceship lands and an alien comes on board their ship. They can't see the alien or his ship. The alien is surprised to see so many people on the ship, as they live alone. After it kills some crew members, they kill the alien with help of the ship computer. I read this about 30 years ago. Any idea of the name and writer?
Added: Book The alien can move outside the visible light When alien was inside the ship his way was blocked by crew member think he panicked and kill them for that reason