TMZ Update: Rough week for Lilo

LOS ANGELES (TMZ) - TMZ has learned ... Lindsay Lohan's lawyer, Shawn Chapman Holley, has resigned as LiLo's lawyer.

TMZ called Holley for comment, and she informed TMZ she is no longer repping Lindsay. Sources tell TMZ Holley resigned earlier today.

As for who Lindsay will be hiring ... TMZ has been told she's a brand new lawyer, Tiffany Feder-Cohen, who was just admitted to the bar in November.

Plus, Kim Kardashian made a late night visit to Lindsay Lohan Thursday night -- stopping by her friend's place before she begins her 90-day jail sentence.

Kim wasn't talking on her way out of the West Hollywood apartment complex -- and though Linds was supposed to appear at a birthday bash in her honor at Las Palmas last night, she was a no-show.

If Kim wants to see more of LiLo after July 20, she'll have to abide by the visiting hours of Lynwood County Jail -- which are Saturday & Sunday from 8:30am - 7:30pm.

And finally, Law enforcement sources tell TMZ ... they have "serious concerns" over Oksana Grigorieva's credibility in connection with her domestic violence claim against Mel Gibson ... because she had money on the brain before making her claim.

TMZ sources say Gibson has emails and other evidence Oksana "tried to extract money from Mel in return for the [explosive] tapes." As TMZ has already reported, Oksana secretly recorded Gibson during several heated arguments back in February.

TMZ was told Sheriff's investigators are concerned that Oksana had contact with civil lawyers and judges while she negotiated a visitation agreement with Mel over a 6-month period but never once contacted police.

Oksana was represented by attorney Eric George, the son of California Supreme Court Justice Ronald George, to handle the visitation case. She went through 2 full days of mediation in May, conducted by two former judges, one of whom was a former federal prosecutor and negotiated a visitation agreement.