Louisville, Ky. — When six-year-old Adam John Walsh disappeared from a Hollywood, Fla., department store in July, his mother was only three aisles away. When 11 -year-old Kathy Kohm disappeared in April, she was out for a jog in the small community of Santa Claus, Ind. Both children were later found murdered.
Julie Patz is still searching for her son, Etan, who disappeared more than two years ago in New York, when she let him walk alone the last half a block to the school bus stop where she could see other children and parents waiting.
Although there are no solid figures on the number of children abducted by strangers and murdered each year, police, private researchers, and social services specialists are convinced that the problem is larger than generally recognized.
FBI Uniform Crime Reports list 2,829 homocide victims under age 20 for 1980, an increase from 2,746 in 1979. The largest number of victims (1,927) is for ages 15 to 19. No details are listed as to how many of these were caused by nonfamily members.
A better known issue is the abduction of children by estranged parents seeking illegal custody.
But abductions by strangers is a tougher problem to solve. There are few, if any, leads for police to follow. Parents often spend considerable amounts of money just trying to get information from police around the nation.
The problem is not limited to big cities - though the mass murders of youth in Houston, Chicago, and Atlanta - have attracted the most national attention over the years. And the problem is not limited to younger children. Teen-age runaways, experts point out, often turn to prostitution and drug dealing to survive on the streets, putting themselves in vulnerable, dangerous, and sometimes fatal circumstances.
Congressional legislation now being considered would make greater use of the FBI's national computer listing of missing persons to help parents of children who have disappeared. The legislation is drawing an unusual amount of public inquiry. The number of cosponsors of the legislation has recently jumped to nearly 100 in the House and 60 in the Senate.
But some experts point out that greater use of the computer listing is not likely to be of great help in locating an abducted child. The listing, for example, would not involve pictures, which, if widely publicized, might provide a tip on the child's location. (The legislation would provide a quicker listing of missing children and a listing of unidentified bodies.)
And, as researchers such as Norman Kent, a Fort Lauderdale, Fla., attorney, point out, local police seldom list runaways as missing persons on the national FBI computer list. This is because many runaways quickly return home. But in an earlier study, Mr. Kent found that three out of every four runaways - male and female - who live on the streets two weeks or more survive by turning to crimes such as prostitution, drug selling, or robbery.
Some children are abducted ''for the purpose of being abused sexually, used in photography (pornography), then exterminated by the people who use them,'' Kent contends.
US Rep. Paul Simon (D) of Illinois claims some 50,000 children disappear from their homes each year, not counting the federal estimate of 1 million to 1.5 million runaways and children snatched by an estranged parent. That estimate - traced back to a House subcommittee staff person who called it a ''very loose figure'' - was based partially on findings by private researcher Kenneth Wooden.
Interviewed here at a national conference on child tragedies, Mr. Wooden said there are no firm estimates on the number of abductions of children by strangers. More research is needed on the topic, he said. But there are indications of the dangers, he added.
Wooden quoted from a letter written by a man arrested on charges of violating child pornography laws: ''One can never predict if or when a kid will squeal to the teacher or fuzz (police). That's one reason you see so many kids who had to be blown away (murdered) after being molested.''
Local officials, including the police, need to be alerted to the problem of abductions of young children and the misuse of some runaways, says Wooden. He also calls for greater enforcement of laws against child prostitution and the use of children in pornography. Parents and neighbors need to be more careful in watching children, he added.
Patient, nonblaming listening by parents to a child's account of being sexually abused is important, experts agree. If a child tells a parent about an incident, and the parent acts horrified or punishes the child, experts say, the child is not likely to mention any future incident if one should occur.
The Reagan administration has proposed budget cuts that will terminate six pilot programs in various states aimed at alerting elementary schoolchildren to the dangers of being approached by strangers. And the President's budget would result in an end to about one-third of the 169 temporary homes for runaways, although Congress is proposing less of a cut, federal officials say. Victims of sexual abuse by strangers are not covered by federal programs for persons sexually abused by a family member, one official says.
Kristen Cole Brown, information officer for Child Find, in New York, offers two suggestions to parents:
1. Telling a child to be careful of strangers is not enough: They may not count as a ''stranger'' someone whom he has seen several times standing on a corner.
2. Teach children to never go with anyone who does not know a family code word.
3. Teach children to scream if approached by someone who does not know that word. Child Find operates a toll-free telephone number for parents and children trying to become reunited (1-800-431-5005).