MARTINEZ -- A jury found a jilted lover guilty Monday of first-degree murder with an enhancement for using a knife in the stabbing death of his ex-girlfriend, according to a prosecutor.

Rafael Zarate, 44, testified during his trial that on Sept. 20, 2011, he fatally stabbed Richmond's Jensy Romero, 30, a single mother of two, in the bathroom of a Richmond restaurant where she waited tables. Zarate, a welder who immigrated illegally to the United States from Mexico, denied the killing was premeditated. Defense attorney Michael Lepie argued it happened in the heat of passion and asked the jury for a verdict of voluntary manslaughter.

Prosecutor Rachael Piersig contended that Zarate was a "classic stalker" who followed Romero for several days after she broke off their relationship and who planned the attack in advance. She asked the jury for a verdict of first-degree murder.

The jury deliberated three days before returning the verdict.

Contact Gary Peterson at 925-952-5053. Follow him at Twitter.com/garyscribe.