Heartbroken Dad Speaks After Pregnant Daughter, Grandkids Are Killed: 'Keep the Prayers Coming'

His voice choking with emotion, the father of slain pregnant mother Shanann Watts on Monday thanked law enforcement for their work on his daughter’s case and Watts’ many supporters for “all your prayers.”

“They are greatly appreciated,” said Frank Rzucek Sr., adding, “Keep the prayers coming for our family.”

Rzucek spoke alongside his son, Frank Rzucek Jr., and prosecutors as they announced formal charges against Watts’ husband, 33-year-old Chris Watts, who is accused of murdering her and their two young daughters — likely in the home they shared in Frederick, Colorado.

Chris was arrested on Wednesday night, when he was accused of killing Shanann, 34, and their girls: 4-year-old Bella and 3-year-old Celeste.

He remains in custody without bond and will return to court on Tuesday to be advised of the charges against him. His attorney did not respond to PEOPLE’s request for comment.

From left: Chris and Shanann Watts
From left: Chris and Shanann Watts

In addition to three counts of first-degree murder with deliberation, Chris is additionally charged with two counts of first-degree murder of a child under the age of 12 by someone who is in a “position of trust” over them, Weld County District Attorney Michael Rourke said at Monday’s news conference.

Shanann, then 15 weeks pregnant, was reported missing the afternoon of Aug. 13, about 12 hours after returning from Arizona on business.

The bodies of her and her daughters were found Thursday on property belonging to Chris’ former employer, an oil and gas company where he had worked as an operator, according to court documents obtained by PEOPLE.

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Causes of death have not been released for Shanann, Bella or Celeste; however, filings from prosecutors and the defense suggest at least some of them may have been strangled.

A motive likewise has not been discussed, but friends of the couple have said there was marital tension.

Says Terry Witt, who lives nearby in Frederick: “You never expect one of your neighbors to do something like this.”

• With reporting by KC BAKER and CHRISTINE PELISEK