A family is anxious for answers after their grandfather flew 18 hours to attend his grandson's graduation, but then vanished, according to reports.

It's been nearly two months since Reuben Waithaka, 73, walked out of his son's house and disappeared on May 15.

Waithaka and his wife, Elizabeth, had traveled more than 8,000 miles from Kenya to witness their first grandson's high school graduation in Alabama before going missing.

Waithaka departed the family home in Calera, around 30 miles south of Birmingham, about 11 a.m. the day they arrived.

He's not been seen since and even missed his grandson's graduation, which took place six days after he vanished.

 "He just arrived; and then he was gone," Waithaka's grandson, Byron, told CNN.

The adoring grandfather planned to attend the graduation and had even brought presents to commemorate the occasion.

CNN said that his bag had pictures of his son at a young age as well as identical outfits for his son, grandchild, and himself.

Waithaka's daughter-in-law, Mary Ngigi Waithaka, posted on Facebook: "Even as our family navigates the worry and uncertainty of my father-in-law going missing this past week, I know he would want us to celebrate this incredible achievement."

According to CBS station WIAT, Elizabeth stated that Waithaka walked out of the house the morning he went missing and appeared disoriented. She first followed her husband, but eventually returned to shut the house doors. When she tried to catch up with him, he had already disappeared.

Waithaka's relatives speculated that he was attempting to return to Kenya.

 "So, if he asks you to take him to a city, especially to Kamboni, that is where he's from," one relative said.

Waithaka’s son, Willington Barua, recently told CNN, “Sometimes I regret why I asked my parents to come for my son’s graduation. I find myself wondering, ‘What would I have done differently?’ Maybe if I hadn’t invited them, my dad would still be with us.”