TULSA, Oklahoma - A Tulsa woman has been waiting years to get answers about her son's death but she still doesn't know what happened to him.

Four years ago, 19-year-old Blayne Davis was found dead at Keystone Lake; and his mother, Chanda Gilbert, still has unanswered questions.

Davis called his mom, told her he was camping with two friends and asked if she could pick him up the next day.

When she called to see if he was ready, she learned the two others returned home without Davis and haven't talked since.

"How do these kids go to the lake and come back without their friend? I just don't understand. Why, if you're innocent, why wouldn't you talk? Why didn't you come to your friend's funeral? Neither boy came to his funeral," Gilbert said.

Those are just a few of the many questions she has about her son's death. Gilbert wants to know how her son ended up face down in the lake about ten yards from shore.

3/9/2011 Related Story: Tulsa Teen Found Dead At Keystone Lake

The medical examiner said he drowned, but the cause is undetermined, so she doesn't know if he was killed or if it was an accident.

Gilbert said she remembers the pain she felt when two men from the Osage County Sheriff's office showed up at her door.

"I said, ‘go ahead, go ahead and tell me my baby's dead,' and the worst words you can ever imagine is, ‘yes ma'am,'" she said.

Gilbert said Davis went to Broken Arrow high, but didn't graduate, and was looking at going to welding school.

She said one of the guys her son was with had cuts and scrapes, but doesn't know where they came from.

"I wish no ill on anybody. I've said a million times, ‘if it was a horrible accident, just come and tell me, just tell me,'" Gilbert said.

Investigators said they also have questions about the case, but not enough evidence to tell them what happened; but they believe drugs played a role.

Gilbert said her life changed on March 9th, 2011 and it will never be the same.

"I lost my baby boy that day at 19 years old," she said.

Investigators said if anyone has information about Davis's death four years ago, they would love to hear it. The Osage County Sheriff's number is 918-287-3131.