A grueling day of technical DNA testimony Friday in the Roger Clemens trial ended on a grim note when U.S. District Court Judge Reggie Walton recessed the proceedings because a juror learned her mother had died.

Walton told lawyers that the juror, number 16, would check in with his clerk on Memorial Day, though it was likely she might be unavailable for the rest of the trial. He said the juror would have to head to Philadelphia to make funeral arrangements.

If the juror is not able to return, there would be only one alternate available, Walton said. Clemens is charged with perjury, making false statements and obstruction of Congress for denying that he ever used steroids or human growth hormone in his 2008 testimony before a House panel.

The sudden end to the proceedings Friday came about 4:30 p.m., and prosecutors had not yet rested their case — as some expected them to do. Their DNA expert, Alan Keel, had testified for several hours prior about DNA evidence that he said linked Clemens to a few cotton balls that his strength coach turned over to federal prosecutors.

Keel had also testified about a needle from the strength coach that possibly contained Clemens’ DNA — rejecting a defense attorney’s suggestion that someone might have planted biological evidence on it because the samples recovered were so small. That might help bolster the credibility of the strength coach, Brian McNamee, who came under vigorous cross examination earlier in the trial. Samples collected from that item would also match 1 in 449 people, according to testimony.

The trial is scheduled to resume 9 am Tuesday.