SAN DIEGO -- A retired social researcher leaves on a cross-country bus trip Thursday to spread the word about Jahi Turner, the 2-year-old boy who was reported missing from a Balboa Park playground on April 25, 10News reported.

Malcolm Lambert, 70, said he is upset that volunteer searches for the toddler ended abruptly about two weeks ago, The San Diego Union-Tribune reported.

"We still need to find that boy, and we need to keep the search alive," Lambert told the newspaper.

Lambert, who said he has conducted social work pertaining to young people for the federal government and several universities, including UCSD, bought a $260 ticket for a Greyhound bus trip that will eventually take him to Frederick, Md., according to The Union-Tribune.

Frederick is the hometown of Jahi's extended family and where the boy lived until moving with his mother and stepfather to San Diego a week before he disappeared.

Lambert said that he will distribute fliers and buttons bearing Jahi's picture at stops along the way, according to 10News.

One of those stops, Lambert said, will be at the Laura Recovery Center. The Texas-based center helps organize searches for children and has assisted locally in both the Jahi Turner and Danielle van Dam cases.

"I hope to get some advice from them on how to restart this search effort," Lambert said.

Jahi's stepfather, Tieray Jones, told police he left Jahi at a playground near the boy's home at Beech and 28th streets with a woman and two other children while he walked a few hundred yards away to buy a soda.

When the 23-year-old returned, his stepson was gone, along with the others.