Why didn't Injun Joe chase Tom in "The Adventures of Tom Sawyer"?

I'm not sure where in the book you are referring to, but it's probably chapter 31, when Tom and Becky are lost in the cave. Tom has the idea to check one of the side passages for an exit, so he takes some kite string out of his pocket, ties it to a rock, and they carefully feel their way in the dark. Then they encounter Injun Joe:

Tom got down on his knees and felt below, and then as far around the corner as he could reach with his hands conveniently; he made an effort to stretch yet a little farther to the right, and at that moment, not twenty yards away, a human hand, holding a candle, appeared from behind a rock! Tom lifted up a glorious shout, and instantly that hand was followed by the body it belonged to--Injun Joe's! Tom was paralyzed; he could not move. He was vastly gratified the next moment, to see the "Spaniard" take to his heels and get himself out of sight. Tom wondered that Joe had not recognized his voice and come over and killed him for testifying in court. But the echoes must have disguised the voice. Without doubt, that was it, he reasoned. Tom's fright weakened every muscle in his body. He said to himself that if he had strength enough to get back to the spring he would stay there, and nothing should tempt him to run the risk of meeting Injun Joe again.

Injun Joe did not recognize Tom's voice, and the light from his candle wasn't enough for him to see Tom. So Tom escaped.