Police have arrested a Lowell man in connection with a fatal shooting in Lawrence last summer.
Rafael Martinez was ordered held without bail after pleading not guilty Monday to charges including murder in connection with the July shooting of Timothy Walker.
Prosecutors say Martinez shot the 20-year-old Walker in the head with a shotgun as he sat with friends on his grandmother's front porch in Lawrence. He was taken to a Boston hospital where he died the next day.
Authorities got a break when they recently released surveillance video of the shooting.
Police allege the 19-year-old Martinez told a friend it was him in the video.
His public defender did not argue for bail.