Hi i am using examine seach in my umbraco project, i have the following issue please help to fix it

if i search letter "J" it should display the name starts with j only.

but it searches like below

Johnson

Ball Jr.
Wells Jr.

Zochowski Jr

I want search result only for

Johnson

My code is

 var searchCriteria = searcher.CreateSearchCriteria();
            IBooleanOperation filter = null;
            var words = s.Split(' ');
            var fields = new string[] { "lastName" }
            foreach (var word in words)
            {
                if (filter == null)
                {
                    filter = searchCriteria.GroupedOr(fields, word.MultipleCharacterWildcard());
                }
                else
                {
                    filter = filter.And().GroupedOr(fields, word.MultipleCharacterWildcard());
                }
            }
            foreach (string id in lawyersToExclude)
            {
                filter = filter.Not().Field("id", id);
            }
            return filter;