Nbc News – Combative cross-examinations, graphic crime-scene evidence, two mothers and one very strange knock-knock joke.

There have been some memorable moments in the trial of George Zimmerman, which hit the midway point Friday when the prosecution rested after two weeks of testimony.

Lawyers for Zimmerman — who has pleaded not guilty to second-degree murder and says he shot 17-year-old Trayvon Martin in self-defense – began laying out their case late Friday and will continue on Monday

Here’s a look back at some of the highlights so far in the legal drama that is playing out a Sanford, Fla., courtroom and being closely watched across the nation:

George Zimmerman’s defense attorney opening statement included a knock-knock joke about the difficulty of picking a jury in the case. He later apologized for it.

The joke: Defense lawyer Don West tried to break the ice with jurors during his opening statement with some humor: “Knock, knock. Who’s there? George Zimmerman. George Zimmerman who? All right, good, you’re on the jury.”

It went over like a lead balloon inside the courtroom and out, and after a lunch break, West apologized to jurors for the attempt at levity.

A photo of Trayvon Martin from the night of the shooting was introduced as evidence during George Zimmerman’s trial on June 25.

The photos: On the second day of testimony, jurors were shown a series of photographs of Martin’s body on the grass at the Retreat at Twin Lakes complex.

One taken by a neighbor showed him face down in the darkness.

Others taken by a police technician showed him on his back and under a tarp.

There was also a closeup of the coin-sized chest wound.

Martin’s father left the courtroom when they were introduced.

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