Robert Interval sentenced to 25 years in prison for killing Christine Mustafa

PHOENIX (FOX 10) -- The man convicted of the murder of missing Valley mother Christine Mustafa has been sentenced to 25 years in prison.

Last April, a jury found Robert Interval guilty of second-degree murder. Interval, 39, could be released in his early 60s.

Interval was tried on one count of premeditated first-degree murder in the death of his missing ex-girlfriend, who disappeared in May 2017. There was an extensive search for Mustafa's remains, including a two-week search of a Buckeye landfill that ended in December of that year. Even though her body was never found, police and prosecutors were confident in the evidence that Interval killed Mustafa and dumped her body.

Interval and Mustafa's relationship was noted to be rocky and abusive. Mustafa had inquired about getting an order of protection and move away from Interval. During the trial, the prosecution presented incriminating text messages, showing that Interval bought mattress covers the day Mustafa went missing, and he was seen outside a trash transfer facility on that day.

In court Friday, a judge told Interval that his actions have devastated Mustafa's father, six sisters, one brother, and two daughters. Interval showed no emotion.

"A blank look on his face," said Mustafa's twin sister, Maryann Mustafa. "There was never any remorse, empathy or sadness in his face throughout his entire process."

A handful of Interval's relatives showed up, asking the judge for leniency, while dozens of Mustafa's supporter breathed a sigh of relief and celebration when the penalty came down. Mustafa's relatives said they will never have closure, as her body is still missing, somewhere among the tons of garbage in a Phoenix landfill.

"I hope he finds the love and forgiveness in that cell, such as that Christine provided to him," said Maryann. "He got what he deserved."

Mustafa's family wore colored ribbons, symbolizing domestic violence and murder. They urge victims to gather the courage to leave their abusers. Now, the cold-blooded words Interval once told Mustafa is haunting Maryann.

"Looked her straight in the eyes, 'I know how to kill you and get away with it,'" said Maryann. "People should not look at that lightly. When people say things like that, you should take them seriously."