NEW : We ask public for information about convicted sex offender Lloyd Lee Welch Jr. Lauren Welch was 12 , her sister was 11 , when they vanished . Their father , Jay Lyon , saw them eating pizza that day . A few years later , he joined the police force .
NEW : Police ask public for information about convicted sex offender Lloyd Lee Welch Jr. Sheila Lyon was 12 , her sister Katherine 10 , when they vanished . Their brother , Jay Lyon , saw them eating pizza that day . A few years later , he joined the police force .