Delaware State Police spokesman Sgt. Paul Shavack confirmed that a DNA sample was taken Wednesday from 46-year-old David Matusiewicz, who was sentenced last week to six months in federal prison for violating probation on kidnapping and fraud charges.
Those charges stemmed from the 2007 abduction of his three daughters in a custody dispute.
Shavack refused to say whether investigators believe Matusiewicz was involved in the Feb. 11 shooting, in which his father killed Matusiewicz's ex-wife and a friend before a scheduled child support hearing.
Matusiewicz told his family in an email obtained by The Associated Press that officials apparently are trying to build a case against him.