WORCESTER ― The third week of Mathew Locke’s quadruple-homicide trial began Monday, with prosecutors beginning to introduce DNA evidence and a defense attorney pressing a witness about an apparent alternative theory of the crime.

A forensic expert testified about a component of saliva which he said was detected in the private areas of the mother and daughter found murdered in their Old Warren Road home. 10, West Brookfield, on February 28, 2018, while a woman staying next door that evening faced intense security scrutiny.

The woman, Christine Tatro, denied telling her ex-husband that the man who owned the house next door had left for an extended period of time on the night of the murders or that he had returned smelling of fuel.

Neither the ex-husband nor the neighbor has so far testified in the case. Tatro testified that her relationship with her ex-husband was contentious.

The jury hears the beginning of the DNA evidence

Jurors Monday morning and afternoon heard the beginning of what is expected to be key forensic evidence against Locke.

Prosecutors said DNA evidence linked Locke, 38, to the murders of Sara Bermudez, 38, and her three children: Madison, 8, James, 8 6 years old and Michael, 2 years old.

Locke is a cousin of Sara Bermudez’s husband, Moses, who was away at work at the time of the murders and testified at trial.

State police forensic expert Kelley King testified at length Monday about items he tested from the master bedroom of the Bermudez home, where authorities found all four victims repeatedly stabbed and burned by fire.

The fire, which they suggested was started with diesel fuel, did not burn, and prosecutors painstakingly introduced into evidence dozens of pieces of evidence found in the room.

King tested many of the items, from bloody and burned clothing to a bloody piece of rope found partially burned at the scene.

As jurors watched in silence, she testified about dozens of individual bloodstains that were found on the walls, carpet, a lamp and other items.

The focal part of her testimony appeared to be a component of saliva, called amylase, she said she found inside and outside the genital areas of both Sara and Madison Bermudez.

King, who has worked in the lab for more than 15 years, took jurors through the process he uses to do his work, from sterilization and protective equipment to a simplified explanation of the tests he does performed.

King testified that he tested swabs collected from several areas of the mother and daughter’s bodies for sperm and saliva.

No sperm was found, she testified. Amylase, an enzyme present in saliva, was found in swabs taken from the inner and outer vaginal area of ​​both mother and daughter, she said.

King testified that he prepared samples from them and submitted them to the DNA lab for further testing.

On cross-examination, Locke’s attorney, Jeffrey S. Brown, pressed King on her work as well as the significance of the test.

King, after a pointed line of questioning, agreed that the test he performed was a “screening” test that did not confirm the presence of saliva, but indicated that it might be present because of the detection of amylase.

She said the samples were sent to a DNA analyst for more conclusive tests. That analyst is expected to testify later this week.

Brown also asked King about the photos he took of the positive amylase screening tests. Projecting them on a screen, he suggested that at least one of the tests didn’t seem to have a line where she indicated.

King said her tests were accurate and confirmed by others. She acknowledged that she did not photograph some of the tests she used to reach her conclusions, saying that was allowed by state police policy because another qualified person present certified the results.

The photos of the tests were difficult to see clearly from the courtroom gallery.

Contentious interrogation

Jurors heard in the afternoon from Tatro, a woman who had ties to both the Bermudez family and their immediate neighbor.

Tatro, on direct examination by prosecutors who called her, said she knew Sara and Moses Bermudez because she had worked for one of Moses’ aunts at Mason’s Grille in Warren.

Tatro testified that she met Sara and Moses Bermudez when they came to the restaurant and that her children had play dates with the Bermudez children on several occasions.

Tatro testified on February 28, 2018, she and her husband were estranged and, while living with their children, were seeing other people.

She said at the time she was seeing a man who lived just down the road at 10 Old Warren Road and stayed there the night prosecutors accuse Locke of killing the family.

Tatro told prosecutors that she and the man she was seeing went to bed around 8 p.m., slept through the night and didn’t hear or notice anything strange.

On cross-examination, Brown asked her about various things he suggested she told her ex-husband.

Tatro denied a series of questions, including suggestions that she had told her ex-husband that the man she was seeing had left the house for a period of time that night and returned smelling of fuel.

The timing of her alleged statements to her ex-husband was unclear from the testimony, which was at times tense, contentious and contained references to several previous police interviews.

Tatro told prosecutors that her relationship with her ex-husband was contentious and that she did not trust him at the time of the murders.

Brown, under cross-examination, suggested that Sara Bermudez had sent Tatro’s ex-husband an email regarding Tatro’s relationship with the neighbor and that the neighbor was upset with Sara Bermudez.

He also asked Tatro if Moses Bermudez and the neighbor once got into a physical altercation at Mason’s Grille.

“I’ve never witnessed anything like that,” Tatro replied.

After Brown’s cross-examination, prosecutors asked Tatro whether, with her ex-husband’s knowledge, she had slumber parties with their children at the neighbor’s house after the murders; Tatro replied that he did.

Tatro also said that the neighbor suffered from heart problems and could not do prolonged physical activity.

Brown — who asked a question that casts doubt on that claim — will have a chance to call his own witnesses after prosecutors rest their case.

The trial is expected to last next week, however.

This article originally appeared on Telegram & Gazette: Mathew Locke Trial: DNA Evidence Introduced, Defense Theory Emerged