Ex-Police Commander's Testimony Aids Defense at Oscar Pistorius' Murder Trial

The top police commander on the scene the night that Oscar Pistorius killed Reeva Steenkamptestified against the Olympic athlete at his murder trial Friday.

But former Col. G.S. van Rensburg may have handed the defense more opportunities to discredit police handling of evidence against Pistorius.

The ballistics expert handling the runner's gun did so without gloves, van Rensburg told the court. And when van Rensburg confronted him, the expert apologized and fetched gloves.

An expensive watch belonging to Pistorius also disappeared during the initial police search of his house, van Rensburg testified.

But probably the key testimony was on Pistorius' bathroom door, which van Rensburg called the most valuable piece of evidence in the case.

The former commander described removing the door, checking that it could be reattached, putting it in a body bag and taking it to his office.

This is critical testimony because the defense argues that the door, as evidence, is contaminated.

If previously given expert testimony based on markings on the door prevails, it could make Pistorius look as though he lied about a detail in his account of events.

Van Rensburg resigned from the police force amid accusations that he mishandled evidence by keeping the door in his office.

In his cross-examination, defense attorney Barry Roux went straight after van Rensburg's credibility, asking him if he understood the importance of telling the truth.

See more at CNN.com.