An FBI technician testified Thursday in the murder trial of a Florida mother that the duct tape found on 2-year-old Caylee Anthony's body was contaminated during testing by another technician.

Heather Seubert, who examined the tape at an FBI lab, told jurors that DNA on the tape did not match the victim, her mother Casey or her grandparents. Instead, it matched another forensic examiner who analyzed the duct tape.

The child's skeletal remains were found in a wooded area near the family's home in December 2008.

Casey Anthony's defense team began presenting its case on Thursday, which was the third anniversary of the last time Caylee Anthony was seen alive.

The 25-year-old mother is charged with first-degree murder in the death of daughter Caylee in the summer of 2008 and has pleaded not guilty. The state contends the child was suffocated by three pieces of duct tape being applied to her face. The defense said in its opening statement that she drowned in her grandparents' above-ground swimming pool.

If convicted, Anthony faces a death sentence.

Under direct examination by defense attorney Jose Baez, Seubert noted other several items of evidence submitted by the prosecution that she tested for the presence of unknown DNA, blood and semen. Those items included pieces of a spare tire cover from the trunk of Casey Anthony's car, a shovel she borrowed from her parents' neighbor, several items of clothing from Casey's bedroom and a shovel found with her daughter's remains.

A few had stains or other areas of interest on them, but none of them showed any testable signs of DNA, blood or semen.

Also, a pair of shorts and remnants of a shirt that were found at the site of Caylee Anthony's remains also didn't show a confirmable presence of blood. DNA could also not be obtained from the items.

The most contentious incident of the morning came just before the lunch break when Baez asked the FBI technician whether she was asked to conduct paternity tests for Caylee Anthony from DNA swabs of the child's own grandfather and uncle.

The defense has claimed that Casey Anthony was abused in the past by both her father, George, and her brother, Lee. George Anthony denied those claims in earlier testimony. Lee Anthony has yet to be asked about it on the witness stand.

"Were you asked to conduct paternity testing for Lee Anthony as a potential father for Caylee Anthony?" Baez asked.

Prosecutor Jeff Ashton immediately objected and Judge Belvin Perry dismissed the jury for its lunch break.

After they had left, Ashton argued that Baez didn't have a "good-faith basis" to ask the question and asked that it be stricken.

The judge made a short inquiry of Seubert, asking her what she was asked to test for by investigators. She had references in her notes that other investigators wanted to know if George and Lee Anthony were candidates for possible paternity testing, but that her lab wouldn't have conducted an actual statistical paternity test. Both Lee and George Anthony were later excluded by additional testing.

Ashton then asked Perry to strike the question from the record. Perry said he would consider it during lunch and rule during the afternoon session.