Marjorie attended a church service with her family members in Bradford, Pennsylvania during the morning hours of May 8, 1938. Her parents decided to have a Mother's Day picnic afterwards in the White Gravel area, which was a 40-minute drive from Bradford. They drove south along US Route 219, following an old railroad grade from Custer City to Marshburg, Pennsylvania. The Wests entered the White Gravel area from Chapel Fork Road in McKean County.

Marjorie picked wildflowers with her older sister Dorothea later during the day. Dorothea recalled that their parents warned them against walking behind a large boulder near the flowers. She said their father and brother checked the area, but there was a chance that rattlesnakes were hiding near the rock. Dorothea left Marjorie alone while she spoke to their mother at approximately 3:00 PM. Marjorie disappeared by the time her sister returned to the area. She has never been heard from again. The girls' mother called the police after an initial search of the area by family members produced no evidence as to Marjorie's whereabouts. Police searched with bloodhounds around the rock and down to the road where the scent trail stopped; there near the road were the violets that Marjorie had picked earlier.

Witnesses reported that two vehicles drove past the Wests' picnic site prior to Marjorie's disappearance. The first was going south to Morrison just before three o'clock. The second was going toward Marshburg just after three. Authorities identified the cars and neither was involved in her case.

A taxi driver in Thomas, West Virginia claimed that he saw a girl matching Marjorie's description riding in a dark-colored sedan with an unidentified man. The sighting took place at 11:38 PM on the night of her disappearance. The driver said that the individual asked him where the nearest motel was located. The driver directed him to an establishment across the street, which did not have any vacancies. The man returned and inquired about a local liquor store. The driver instructed him to stop at a bar down the road. The driver identified Marjorie as the man's passenger several days later, but man's identity remains a mystery.

Investigators determined that the approximate travel time along US Route 219 between the White Gravel area and Thomas, West Virginia was eight hours. If the individual abducted Marjorie around 3:00 PM, they would have arrived in Thomas by 11:00 - 11:30 PM that evening. Authorities were unable to confirm the child's identity.

There was speculation that Marjorie was taken to Canada by other family members, while others theorized that she may have fallen down an abandoned oil well near White Gravel. Some people believed that Marjorie may have been abducted and taken somewhere in the south or southwestern United States. Additional speculation pointed towards the Tennessee Children's Home Society near Memphis, Tennessee. The facility was operated by Georgia Tann, who was initially lauded for placing at-risk children in adoptive homes. Authorities eventually learned that Tann had kidnapped over 1200 young children during the years 1932 through 1951. The majority of victims were abducted from states bordering Tennessee, although some children resided in Connecticut. Judge Camille Kelly approved Tann's custody bids for the majority of the victims. Tann placed most of the children with childless couples in New York City, New York or Los Angeles, California.

None of the theories have been proven and no one has been implicated in Marjorie's disappearance. (Information retrieved from NamUs.gov)