By Tony Hanson

PHILADELPHIA (CBS) - An attempted robbery and the chilling details of a series of life and death battles are detailed in court by witnesses and video.

Three people were shot and one of them, a Good Samaritan who tried to intervene, died during the March incident at the crowded La Familia Latina grocery store in North Philadelphia. Two men have been held for trial.

Witnesses say an armed, masked man announced the robbery and then shot the store owner, who still managed to fight with the gunman, shooting him during a struggle that lasted over 20 seconds. Then the gunman fled.

That’s when Good Samaritan Rafael Del Valle took off after the robber, but authorities say he was also pursued and gun down, executed after he was shot and fell.

His sister, Yessenia Colon Del Valle, endured as much of the video as she could.

“He was brave. The hard part for me was watching him fall down, as Angel, I know it was him because you could tell it was him, shot him.”

But defense attorneys, who have challenged key evidence including the prosecution’s interpretation of actions on the video, say Edward Friedland and Angel Nieves will plead not guilty.