Four workmates of a young waitress who killed herself by jumping off a building have been convicted and fined a total of $335,000 over relentless bullying before her death.

Brodie Rae Constance Panlock, 19, was subjected to the humiliating bullying by workmates at Cafe Vamp in Hawthorn, in Melbourne's east, before she threw herself from a multi-storey car park in September 2006.

Former workmates Nicholas Smallwood, 26, now of Queensland, Rhys MacAlpine, 28, of Kooyong, and Gabriel Toomey, 23, of Melbourne, all pleaded guilty in the Melbourne Magistrates Court to failing to take reasonable care for the health and safety of persons.

The cafe's owner Marc Luis Da Cruz and his one-man company MAP Foundation pleaded guilty to two charges, including failing to provide and maintain a safe working environment.

All four men were convicted on the charges, with magistrate Peter Lauritsen on Monday describing their actions as "the most serious case of bullying" and saying he would have doubled the penalties if they had not pleaded guilty to the charges.

Smallwood was fined $45,000, MacAlpine was fined $30,000 and Toomey $10,000.

Da Cruz, 43, was fined a total of $30,000 while MAP Foundation was fined a total of $220,000.

During earlier hearings, tearful family and friends of Ms Panlock heard distressing details in court of her ordeal at Cafe Vamp, where she worked between June 2005 and September 2006.

Ms Panlock's distressed mother Rae had to leave court several times as Mr Lauritsen delivered his findings.

Prosecutor Gary Livermore told a pre-sentence hearing on Friday that witnesses had seen Smallwood and MacAlpine pour fish oil into Ms Panlock's kitbag and then pour it over her hair and clothes, reducing her to tears.

He said they had also engaged in indirect bullying, such as calling her fat and ugly, spitting on her, gossiping, exclusion and failing to intervene when she was being bullied.

He said Da Cruz was aware of the bullying and on occasions told them to "take it out the back".

Mr Lauritsen was told that Ms Panlock had tried to commit suicide in May 2006 by ingesting rat poison with beer after being rejected by Smallwood, with whom she'd had an intimate relationship.

Mr Livermore said that after that incident Smallwood put rat poison in her bag, and MacAlpine urged her to take it, while her tormenters had taunted her about her attempted suicide.

The three men no longer work at the cafe.