The family of a young man who went on a deadly shooting rampage in two Colorado religious centers before killing himself said Wednesday that they are "groping for answers" and praying for the victims' families.

Matthew Murray's family said in the statement that they will hold a private funeral for him later this week.

"We are lost in grief as we prepare to bury our beloved son, Matthew. We loved Matthew with all our hearts, and we are groping for answers as we try in vain to understand the events of last Sunday," the family said.

Two services were being held Wednesday to remember the four people Murray, 24, killed on Sunday when he opened fire first on a missionary center and then on a megachurch some 65 miles away.

On Tuesday night, friends and parishioners of Murray's uncle, Phil Abeyta, gathered at the Denver church where he serves as pastor to pray for victims, the Murray family and Matthew Murray.

"They are grateful for your love and support," Abeyta said of the Murray family as he addressed the gathering of about 70 at His Love Fellowship.

The family spent Tuesday quietly, "in reflection and prayer for the families of the victims and those who were injured," Abeyta said.

Murray killed two people at Youth With a Mission, a training center for missionaries in the Denver suburb of Arvada, early Sunday. About 12 hours later, he killed two more people at the New Life Church in Colorado Springs. In between the shootings, Murray is believed to have left several posts on a Web site's forum warning that he wanted to kill Christians.

Joe Istre, president of the Association of Former Pentecostals, which operates the site, told The Associated Press on Tuesday that he and other forum participants had grown familiar with the frequent and disturbingly dark poetry and obsessions of one participant, whose nickname was nghtmrchld26.

But when that same author _ believed to be Murray _ left the posts on the day of the shootings, a forum participant immediately contacted the FBI, Istre said.

"I'm coming for EVERYONE soon and I WILL be armed to the @#%$ teeth and I WILL shoot to kill," one threat posted by nghtmrchld26 said.

"My reaction was disbelief, but then almost horror," Istre said of Murray's violence. "This guy was posting on our forums, and we are a support group out to help people, to try to get them to calm their fears and get them into a productive life. And here we are conversing with a dude who was a killer."

Arvada police spokeswoman Susan Medina said police cannot say with certainty who nghtmrchld26 is. Istre also said his forum agreed to turn over all relevant information, and provided the FBI the Internet Protocol address of nghtmrchld26 to help confirm the poster's identity.

The Denver Post reported Wednesday that Murray also was apparently posting to a different forum under the name DyingChild_65, and may have foretold of his rampage there, too. In one posting, he references the one of the Columbine killers and the gunman who opened fire at Virginia Tech. He also mentioned Ricky Rodriguez, who stabbed a prominent member of a church once known as the Children of God, then shot himself in the head in 2005. The group had been accused of sexually and physically abusing child members during the 1970s and 1980s.

"Like Cho, Eric Harris, Ricky Rodriguez and others, I'm going out to make a stand for the weak and the defenseless this is for all those young people still caught in the Nightmare of Christianity for all those people who've been abused and mistreated and taken advantage of by this evil sick religion Christian America this is YOUR Columbine," the newspaper quoted the post as saying.

The Gazette of Colorado Springs reported Murray also posted rants under the name "Chrstnghtmr."

Murray, 19, was dismissed from Youth With a Mission in 2002 for what the training center has described only as health reasons. Youth With a Mission maintains an office at New Life Church's World Prayer Center.

An autopsy Tuesday determined that Murray killed himself with a bullet to the head after he was brought down by gunfire from a volunteer security guard at the church, authorities said.