An unregistered sex offender was arrested at 6:50 a.m. Monday at Forest Hills station after a concerned citizen told transit police they saw him taking pictures of kids on the train.


Vincent Lucas, 49, of Lowell, told police he just got a new phone and "was playing around with it," but a subsequent investigation discovered that Lucas had failed to register as a sex offender.


Transit police credited their "If You See Something, Say Something," initiative for the report, saying the witness followed the MBTA's request to be on the look out for suspicious activity.


"This is yet another example of the importance of partnership between the Transit Police and our MBTA community. As always, 'If You See Something Say Something,' a transit police spokesman said in a statement.