SAN ANTONIO (AP) — A Texas police chief says investigators hope surveillance video will lead to answers in the killings of an 18-year-old pregnant woman who disappeared before Christmas and her boyfriend, both of whom were found shot in the head in a car and may have been dead for days.

Police on Friday had not named a possible motive or suspects as family and friends mourned the deaths of Savanah Nicole Soto, 18, and Matthew Guerra, 22. Soto’s family has said she was overdue to deliver her baby and had been scheduled to have an induced labor when she went missing last week.

The Bexar County Medical Examiner’s Office ruled both deaths homicides caused by gunshot wounds to the head.

The couple were found Tuesday in Guerra’s car outside a San Antonio apartment complex, a crime scene that San Antonio Police Chief William McManus originally described as “very, very perplexing.”

On Thursday, police asked the public for help identifying two people seen in surveillance video that included the car and was recorded before the bodies were found.

McManus would not say whether investigators believe the couple was dead when the video was taken.

“Detectives are hopeful that surveillance video will lead to the events leading up to their death,” McManus said.

The video shows Guerra’s car briefly pulling up next to a pickup truck at a spot close to where the couple was found, McManus said. A person gets out of the truck and approaches the driver’s side of the car. Another person is seen briefly stepping out of Guerra’s car, but McManus said they do not believe that person was one of the victims.

He has described the case as a capital murder investigation and called it “a heinous act.”

Soto had been scheduled to have an induced labor at a hospital last Saturday night, her family told KENS-TV. But her mother said she got no answer earlier that day when she knocked on the door of Soto’s apartment in the suburb of Leon Valley.

The family spent Christmas night searching the area. On Monday, Leon Valley police issued a missing-person alert for Soto and later said Guerra also could not be found.

At a vigil in San Antonio on Thursday, Savanah’s grandmother, Rachel Soto, described Savanah as a “funny girl” and said she loved everybody and loved to live life. She said her granddaughter was looking forward to becoming a mom for the first time, the San Antonio Express-News reported.

“I just pray to God that she took her baby with her and that she is at peace,” Rachel Soto said.