Daggers dominated the first half and were close to edging in front in the 16th minute.
Jon Nurse raced away from defender Inigo Calderon and his low drive could only be parried by goalkeeper Casper Ankergren into the path of Bas Savage, whose tame effort was miscued off the line by Marcos Painter, back onto Savage and up onto the crossbar.
The visiting keeper was called into action again several times before the interval, with Ankergren denying Savage, Nurse and Danny Green.
The hosts continued to look more threatening at the start of the second half, with Damian Scannell and Savage both going close, but it was Brighton who broke the deadlock in the 59th minute. Craig Noone crossed for Murray to volley in from six yards.
The visitors continued to hang onto their frail lead as Peter Gain had two efforts blocked, but Brighton held firm to move 13 points clear at the top.
Ryan Harley's penalty earned Exeter a 1-0 win over Swindon as the Robins' miserable winless run extended to 17 matches in foggy Devon.
The first half was largely a non event.
Matt Ritchie's shot inside the first 30 seconds was the closest either side came to scoring, but his 25-yard drive was well saved by Exeter goalkeeper Ben Hamer.
Matt Taylor headed onto the roof of the net as Exeter started the second half well, while Alan Sheehan brought a fine save from Hamer with a free kick from 25 yards for the troubled Robins.
Exeter broke the deadlock with 11 minutes remaining when Calvin Andrew handballed Billy Jones' corner kick inside the penalty box. A penalty was awarded and Harley rolled the ball down the middle of the goal as David Lucas dived to his right.
Swindon responded with Andrew firing wide shortly after Harley`s goal, but that was as good as it got for the Robins, who on this form look certainties for relegation to League Two.
Rochdale made it four straight wins after a 2-0 victory against Charlton at Spotland.
The result stretched the Addicks' run without a win to 11 games as goals either side of the break from Jason Kennedy and Craig Dawson sunk Chris Powell's team.
Dale goalkeeper Owain Fon Williams saved angled drives from Scott Wagstaff and Therry Racon inside the opening five minutes and later kept out Joe Anyinsah's shot.
Keith Hill's side grabbed the lead in the 34th minute. Robbie Williams' centre was cut out by Jose Semedo, but his clearing header dropped invitingly to Kennedy on the edge of the area and he sent a stunning volley into the bottom right-hand corner of Rob Elliott's net.
The goal ignited Dale and before the break Chris O'Grady fed Matt Done for a clear view at the target, but he pulled his shot wide of the upright.
They made the result safe in the 75th minute when Dawson scrambled the ball across the goalline after Done's corner caused panic in the Charlton six-yard box.
Goals from Michael Spillane, Jeffrey Schlupp and Sammy Saunders gave Brentford a 3-1 victory over a Sheffield Wednesday side left hovering just above the relegation zone.
Spillane gave the visitors a third minute lead, planting a firm header past Richard O'Donnell from Nathan Byrne's corner.
Wednesday's Gary Madine headed over before Rob Jones equalised with a near-post header after meeting a Gary Teale corner.
Brentford regained the lead six minutes later when Lewis Grabban nipped in ahead of Jones and crossed to Schlupp who headed in from close-range.
Wednesday substitute Jermaine Johnson threatened with a strong run into the area before trying an angled shot which went beyond the far post.
Brentford substitute Saunders completed the scoring in the 82nd minute, beating O'Donnell with a superb 25-yard free-kick which left the keeper rooted to the spot.