Lorna Riggs (née Cole) is a police officer for Internal Affairs of the Los Angeles Police Department. Starting in Lethal Weapon 3, she becomes a main character in the series. At first, she pitied Martin Riggs after hearing him say rude jokes behind her back. It isn't until the temporary loss of Riggs' partner Roger Murtaugh that he develops a good relationship with Cole and together (with Murtaugh eventually returning), they stop Jack Travis' arms dealership on the black market.
She was portrayed by Rene Russo.
Lorna Cole is an police detective of LAPD. Like Captain Ed Murphy, she takes her job seriously and does not appreciate Riggs' offensive jokes with her back turned. Cole starts to take a liking to Riggs when he helps her on the case of Jack Travis' arms dealership. Cole is also really smart and applies two bullet proof vests underneath her clothes, which protected her from the armour piercing bullets. She begins a romantic relationship with Riggs which leads to her being pregnant, but she isn't married. Riggs does marry Cole eventually when he lets go of his tragic past of his late wife, Victoria.
Lorna Cole is a slender woman with fair skin, long brown hair and blue eyes. She sometimes wears a headband to keep her hair out of her face. She usually wears long-sleeved shirts with jeans.
Lorna is first seen in the elevator with Martin Riggs and Roger Murtaugh, who are demoted to patrolmen after mishandling a bomb they tried to dismantle went south. Riggs whispers to Murtaugh that she looks Portuguese, and making up some insulting jokes while Murtaugh tells him she is a cop just like them. Cole heard every word and as soon as she steps out of the elevator, proceeds to the interrogation office asking to see suspect Billy Phelps, who was pulling off a armour car bank robbery heist and was stopped and arrested by Riggs and Murtaugh. After finding out she is on the case, too, Cole tells them it is an Internal Affairs case now and talks back to Riggs, reusing one of his rude jokes.
Quickly, they talk to Captain Ed Murphy about why the Cop Killer case has been transferred to internal affairs. Cole's boss Herman Walters is also present.
Unknown to all three of them, Billy Phelps was shot to his death by Jack Travis in the interrogation room. Travis was covering up from the camera while using his valid credentials, but was never aware he was caught by a camera in the interrogation room installed by Internal Affairs at every station 6 months prior. According to Captain Murphy and Lorna, Lieutenant Jack Edward Travis was one of them in the LAPD, who was one brutal cop and could beat a confession out of anyone. Travis had some bad reputations and had charges pressed against him. While on a stakeout with his partner, he left for a cup of coffee and never came back, thus going AWOL.
A couple of days later, while still talking about the case, Cole speaks again to Riggs and continue talking about the transferred case to Internal Affairs in the men's bathroom. Bomb Squad leader Becker warns Riggs about talking to Cole. While still arguing about the case, Riggs mentions to Cole about the falling out of his partner Murtaugh the previous day, with the incident involving Darryl Smithers after being shot at, to which Cole stops Riggs and tells him she knew about and is sorry it happened. Rather than argue further, the two both decide to be partners on the case and solve it together.
Cole takes Riggs to her office to investigate more information on one of the recovered guns (a MAC-10) from the foiled robbery a few days back. They both discover that the only person who could get his hands on such weaponry would have to be a former cop himself. Their conclusion: Jack Travis.
The two stake out a warehouse, believing it is where Travis keeps his arsenal of stolen firearms. Before they can proceed any further, they are both confronted by a Rottweiler. Cole questions whether or not she should shoot the dog, but Riggs tells her it's not a good idea and he will handle it. While Riggs is taming the dog giving him dog biscuits, Cole says she will leave them both be.
She comes out of hiding when Riggs is held captive by one of Travis' thugs Hatchett and another strangles him to a steel beam. She gets captured, but she uses her hand-to-hand martial arts skills on some of them, with Riggs doing the same before they take off in the pickup truck with that has boxes of guns Hatchett was preparing to bring to Tyrone. They stop and wait for the dog to come with them.
Later on, at Cole's place, they prepare to dress their wounds from the fight at the warehouse. They show each other their scars and cuts from their battles in the past they each went through. Just when Riggs grabs Cole, Cole ends up sharing a kiss with him, and then she throws him down to floor where they continue making out in the process.
The next day, Lorna is seen present with Riggs, Murtaugh, and Murtaugh's family at Darryl's funeral, where Roger tries to extend his condolences to Mr. and Mrs. Smithers, only to have Mrs. Smithers slap him in the face before crying any further. Mr. Smithers, however, advises Roger to find the man who sold the gun to Darryl.
Soon, they all go after the sources of where the guns are coming from and being sold to, one-by-one. They eventually find Tyrone and get him to talk threatening to have run Lorna run over his face with a truck, and reveals to them that it's Jack Travis. Lorna speeds with the truck in reverse, to have Tyrone pass out scared.
Later, they go to another warehouse to find Hubie, who is supposedly on parole and working with Travis at the same time, and the latter try to interrogate him, only to be interrupted by some other henchmen of Travis. Here, Lorna is seen showing her hand-to-hand combat skills again, until the henchmen take off, before interrogating Hubie any further.
The next day, at the station, after Travis and his henchmen impersonating police officers kidnap Captain Murphy to gain access to the arms storage facility, Riggs, Murtaugh, and Lorna go after the storage facility where Travis and his men steal the weaponry and the armour piercing "cop killer" bullets, while being accompanied by Officer Edwards for backup. There, a gunfight ensues, and when Edwards is fatally wounded, Cole tends to him.
Later that night, Riggs and Murtaugh go to Rancho Oroya, where Jack Travis and his henchmen are at building their illegitimate establishment. They're joined along with Lorna. They start up a gunfight taking on Travis' henchmen one-by-one, and they set the entire development site on fire. Right after Lorna shoots a henchman, backing up Riggs and Murtaugh, Travis comes out of nowhere and shoots her with his armour piercing bullets, thinking he killed her. Playing dead, though injured, Riggs sees Lorna's body and thinks she is really dead and now turns his anger on Travis.
After the battle, Riggs tends to Lorna and sees she had on two bulletproof vests, to prevent any further damage, though still a couple of bad ones. Riggs tells her he loves her, just before she is taken to the hospital.
The next morning, after Murtaugh was going to retire, he decides not to after all and continues on the force for another 10 years before retirement. As he and Riggs are leaving for work, Murtaugh warns Riggs to stay away from Rianne after seeing they kissed, but Riggs lets him know he's already spoken for by Lorna and going her up from the hospital in the afternoon, to which Murtaugh says, "You're serious?" It indicates that Riggs and Lorna have decided to be in a committed relationship together after all they've been through together.
In this film, Lorna is pregnant, and is considering marriage, but at a tough time. Her fiancé Martin Riggs comes home with fast food and has a talk with Lorna about getting married. She assures Martin that she may very well consider it. She also tells him that Rianne has secretly married a police officer named Sergeant Lee Butters and is having a baby with him, since Roger would be upset about her dating cops. Upon telling him all this, she makes him swear he won't say anything about it to him until the baby has been born.
She comes to the Murtaugh's house, and sees that Roger had been watching over the Hongs until they've been granted asylum. A couple of days later, Wah Sing Ku and his men come to the Murtaugh's house and holds her, Rianne, and Trish hostage, while some of Ku's men have kidnapped the Hongs. Riggs and Murtaugh come back to see what's going on. Lorna handles a few of Ku's men and is about to take off with Rianne and Trish, until they are captured again. After Riggs and Murtaugh have been overpowered by Ku, they're all tied up with duct tape and left to die after the house is set on fire. Fortunately, one of Hong kids, Ping, who managed to hide to avoid being kidnapped, comes out from hiding and cuts her and all the others free, and they all escape the burning house alive and unharmed.
The next day, in the night, Riggs and Lorna are still talking about their plans to marry. They're being attacked again on the train tracks by Ku's henchmen, and just where the train is about to hit them, Lorna shot at the car and Riggs goes forward, allowing their assailants be hit by the train. Afterwards, Lorna is taken to safe place to watch over Ping and all the other Hongs after they've been rescued, while Riggs, Murtaugh, Butters, Ng, and some other detectives go after Ku and his men at the pier.
A couple of days later, after Riggs and Murtaugh take down Ku and his men, and after Riggs visits Victoria's grave, Lorna pages Riggs, letting him know that she's about to have the baby. She insists on "getting married" before having the baby. Although their marriage wasn't official, she and Riggs just wanted to hear the words before the baby comes, and it was done by a Rabbi, named Rabbi Gelb, who unofficially wedded them. Soon after, both her and Rianne give birth to their babies in the same hospital on the same day. Afterwards, she and Riggs and their baby, Rianne and Butters and their baby, Trish, Roger, Nick, Carrie, Leo, and Captain Ed Murphy all have their picture taken for the family photo.