A suspect has been arrested in connection with a brutal 20-year-old cold case murder of a young Arizona girl. 

The Phoenix Police Department (PPD) confirmed to Fox News Digital in a statement that Sergio Francisco Reyes, 37, was arrested on Wednesday for the 2004 murder of 15-year-old Elena Lasswell.

Reyes' arrest comes exactly 20 years, to the day, after Lasswell was killed in her Phoenix home on July 10, 2004.

"On July 10, 2024, exactly 20 years after the horrific murder of then 15-year-old Elena Lasswell, detectives with the Phoenix Police Department's cold case unit have arrested and booked 37-year-old Sergio Reyes for multiple violent felonies to include sexual assault and 1st Degree murder," Sgt. Brian Bower of the PPD Public Affairs Bureau said in a statement. 

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37-year-old Sergio Francisco Reyes arrested for murder of Elena Lasswell

Phoenix police arrested Sergio Francisco Reyes, left, in connection with the murder of Elena Lasswell, inset, 20 years to the day the killing happened. (Katie Tourville/FOX 10 Phoenix)

Police said that Reyes was extradited from Mexico on Wednesday, and booked into Maricopa County Jail for several violent felony charges.

It was just after 8 p.m. on July 10, 2004, when Phoenix police responded to a house in the area of 23rd Ave. and Thomas Road.

Officers and Phoenix fire personnel were directed to a room where they found the victim, identified later as Lasswell.

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Elena Lasswell (L), and Sergio Francisco Reyes (L)

Sergio Francisco Reyes, 37, was extradited from Mexico on July 10 and booked into Maricopa County Jail on multiple charges, including sexual assault and 1st-degree murder of Elena Lasswell, the Phoenix Police Department said in a press release.  (FOX 10 Phoenix/Phoenix Police Department)

"Emergency lifesaving measures were attempted but Lasswell did not survive her injuries and was pronounced deceased on scene," police said in a statement.

Officers were able to contact several witnesses and then turned the case over to homicide detectives, who took over the investigation and developed leads with no direct information as to who killed had Lasswell.

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37-year-old Sergio Francisco Reyes

Phoenix police arrested Sergio Francisco Reyes, left, in connection with the murder of Elena Lasswell, 20 years, to the day, after the killing happened. (FOX 10 Phoenix)

Detectives, not having any suspects, presented the case to Silent Witness, asking for community support in identifying a suspect. However, investigators ran out of leads, causing the case to go cold. 

In 2012, police said cold case detectives used DNA collection techniques and were able to identify a profile that matched Reyes. 

In March 2013, DNA evidence was processed and confirmed Reyes as the lead suspect. 

Reyes, who police said was living in Mexico at the time, was indicted by a Maricopa County grand jury in 2014. This then prompted the start of the extradition process with help from U.S. Marshals Service to locate and arrest Reyes for the alleged brutal sexual attack and murder of Lasswell.

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Katie Tourville (L) and Elena Lasswell (R)

Elena Lasswell's aunt, left, told FOX 10 that the family does not wish revenge on her suspected killer; they just wanted him caught so he can't hurt anyone else.  (Katie Tourville/FOX 10 Phoenix)

FOX 10 Phoenix spoke with Lasswell's aunt on Wednesday afternoon about the emotions the family is feeling.

"Knowing that someone is being held responsible feels awesome," Katie Tourville said. "It's been a long haul, and thank God for Phoenix PD. They have been absolutely amazing. I just really felt that they were on the right trail, and that they would get it. I just didn't know when."

Elena's mother had passed away in the years since her daughter's murder, but Tourville said the mother's wish was not revenge.

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"She wanted him to be caught so he couldn't hurt anyone else," Tourville said.

According to jail records, Reyes is being held on $1.5 million bond, and his next court appearance is scheduled for July 17.