WAGONER, Oklahoma - Wagoner County Sheriff's deputies have arrested a third person in connection with the 2006 death of Jarret Clark of Broken Arrow. He had just graduated from high school when someone beat him and left him to drown in Fort Gibson Lake.

Anthony Scott Wallen, 30, was booked into the Wagoner County jail on a charge of first-degree murder Tuesday morning.

"This is another step in the process of achieving justice for Jarret Clark," said Wagoner County District Attorney Brian Kuester.

Tammy and Eric Slater, Jarret's parents, were present as Kuester discussed the arrest.

"Very emotional day," said Tammy Slater. "But it's a day of justice for Jarret. So this is a day for Jarret; this is Jarret's day."

Wallen's arrest followed the arrest in May of Dayna Miller, 27, of Wagoner and in January of Courtney Manzer, 24, of Broken Arrow. Both are charged with first-degree murder.

Sheriff Bob Colbert said a fourth possible suspect died in a car crash a couple of years after Clark's death.

Clark, 18, was found dead in 2006 at Fort Gibson Lake, just days after his Broken Arrow High School graduation. Clark went missing after he and others went camping near the Wahoo Bay area.

Four days after a missing person's report was filed, Clark's body was found. The state Medical Examiner's Office said the cause of death was by drowning.  

His parents are still feeling the pain of the day they found out.

"It's been a long journey," Tammy said. "Every day's been pretty difficult. Some days are harder than others. And every day I still ask 'why?'"

An affidavit shows Wallen admitted to hitting and kicking Clark in the head several times that night. The prosecution expects a witness to testify that Wallen admitted to them: "I hit him too hard. I killed him."

The trial - or trials - haven't started yet, but during Tuesday's news conference I asked the Slaters what they had to say to the people who prosecutors say did this to their son.

"Why?" Tammy Slater asked. "Why did they feel they had to do this to my son. Why?"

Authorities don't anticipate any more arrests, but Kuester is asking for anyone who may know more about this case to call  his office, or the Wagoner County Sheriff' office.

The district attorney says a trial in this case wouldn't happen until next year.